Abstract
Purpose: :
To investigate the role of complement in laser-induced choroidal neovascularization (CNV) in mice
Methods: :
Retina photocoagulation lesions in C57BL/6 mice were generated with an Iridex Oculight® GLx 532 nm laser (3 lesions/eye, 6 lesions/mouse, 10 mice/cohort, yielding 60 data points per cohort). On day 7, mice were injected iv with vascular label and euthanized. CNV lesions were photographed by fluorescent microscopy and lesion area was measured with Axiovision software. Data was masked during image acquisition, application of exclusion criteria, and analysis. Wild-type and complement-deficient (or drug-treated) mice in each experiment were age and sex matched and derived from a single vendor. Inter-group differences were analyzed by one-way analysis of variance (ANOVA) with a Neuman-Keuls post hoc analysis or an unpaired two tailed t test. Mice investigated included knockouts (KO’s) of C3, factor D, factor B, C5, C5a receptor or C6 on a C57/Bl6 Jackson background and CFH KO’s and C3 KO’s on a Taconic background. In some experiments, wild type mice were treated with complement modifying drugs including systemic administration of cobra venom factor, a serine protease inhibitor (Nafamostat), a covalent inhibitor of factor D (Biocryst), and a LMW C5aR antagonist (PMX53) as well as intravitreal administration of PMX53.
Results: :
The areas of CNV were significantly larger in C3, C5 and C6 KO mice compared to C57/Bl6 mice on a Jackson background. The areas in Factor D & B KO’s were not different from C57/Bl6 controls. C3 KO mice on a Taconic background developed CNV lesions with areas similar in size as C57/Bl6 controls. Factor H KO and heterozygote mice on a Taconic background developed significantly smaller areas of CNV compared to C57/Bl6 controls. All drugs tested did not significantly inhibit the area of CNV. We also observed that Taconic mice develop an area of CNV ~ 3 fold larger than mice from the Jackson lab.
Conclusions: :
We note that the mice derived from different vendors have markedly different responses to laser photocoagulation. The differences in CNV area observed between KO mice and controls may be explained by variation in the origin of mice. We reccommend that sibling controls are used for future experiments.Our experimental results to date indicate that complement deficiency plays at most a minor role in mouse laser-induced CNV. Our observations are in contrast to published findings from other groups that found complement deficiency reduced the size or completely inhibited the area of laser-induced CNV. We note that laser-induced CNV in mice has a different pathogenesis than wet AMD
Keywords: choroid: neovascularization • pathology: experimental • immunomodulation/immunoregulation