SUMMARY: Current anti-VEGF-A therapies inhibit choroidal neovascularization (CNV) in a subset of patients
with neovascular age-related macular degeneration (NV-AMD). However, long-term treatment with such anti-
VEGF-A therapies may impair physiological functions of the choriocapillaris and retina for which VEGF-A is
needed. Moreover, disease progression can occur despite continuous anti-VEGF-A treatment. Thus, novel
therapies for NV-AMD are urgently needed that target specifically disease-associated mechanisms without
impairing growth factors and cellular pathways that are required for homeostatic functions of the retina and
choroid. Inhibiting the inflammatory pathways that promote CNV would be such a promising novel approach that
would not interfere with the normal functions of healthy retinal and choroidal cells. In this context, the
inflammasome, a proinflammatory protein complex that promotes pathologic angiogenesis through the
generation of IL-1b and which has been reported to be activated in AMD, has become an area of much interest
in the AMD field. However, previous studies have focused mainly on the NLRP3 inflammasome in RPE cells and
conflicting data have resulted in an unclear picture of the role of the inflammasome for AMD pathogenesis. By
utilizing a genetic mouse model of NV-AMD, Vegfahyper mice, we provide now new data that resolve key open
questions in the AMD field and help explain some of the conflicting data. Our findings demonstrate that
inflammasome activation in activated macrophages and microglia but not in RPE cells promotes CNV. Thus, a
lack of inflammasome activity in the RPE does not mean that the inflammasome does not play a role in AMD
pathogenesis. Furthermore, we provide evidence that inflammasome activation can occur in CNV macrophages
and microglia despite NLRP3 deficiency. Based on these findings we propose that activation of both NLRP3
inflammasomes as well as non-NLRP3 inflammasomes in macrophages/microglia promotes CNV. Our new data
in Vegfahyper mice and in eyes from patients with NV-AMD suggest that the AIM2 inflammasome is a key
contributor to overall inflammasome activation in these macrophages and/or microglia. Thus, we hypothesize
that both the NLRP3 and the AIM2 inflammasomes promote NV-AMD through their activation in macrophages
and microglia that infiltrate and induce early CNV. Notably, a role of the AIM2 inflammasome for AMD
pathogenesis has previously not been considered. Thus, our preliminary data and published work provide a
strong scientific premise for these hypotheses, and the proposed experiments have a high novelty, high
rigor, and strong clinical relevance, as their outcome will serve as a framework for novel therapies that target
inflammasome activation in patients with NV-AMD. Our proposal will utilize both genetic as well as pharmacologic
approaches in two well-established mouse models of NV-AMD as well as experiments in human AMD eyes, to
define the roles of AIM2 and NLRP3 inflammasomes for NV-AMD.