Evaluating the role of inflammasome activation in models of pathological ocular angiogenesis

Pathological angiogenesis in the eye remains at the center of a myriad blinding diseases, including neovascular age-related macular degeneration (nvAMD). Elucidating the mechanisms by which these invasive neovessels proliferate into normally avascular regions is of critical importance. The past two decades of research have identified the inflammasome, a component of the innate immune system responsible for sensing foreign and endogenous danger signals, as a potential mediator of aberrant angiogenesis. However, several previous conflicting reports on the role of inflammasome in this context have only brought to light a clear gap in knowledge.

Here, we expanded the experimental laser-induced choroidal neovascularization (CNV) model, considered to be the field standard, to include subretinal administration of disease-relevant inflammasome agonists. In doing so, we observed increased CNV volume in wild type mice but not mice lacking inflammasome constituents, an effect that was mediated by key components of the NLRP3 inflammasome pathway. Additional studies identified the role of interleukin-1β (IL-1β) in promoting chemotaxis and macrophage ingression to the lesion site.

Coincident with our work in expanding the CNV model, we also developed a first-of-its-kind experimental model to assess how physical activity affects the development of CNV lesions in exercise-trained mice. Interestingly, exercise-trained mice exhibited a significant reduction in CNV volume and F4/80 immunopositivity that was independent of sex and distance traveled. Fluorescent in situ hybridization signals against mRNA of several pro-angiogenic and pro-chemotactic factors were also reduced in the exercise-trained cohort, suggesting that physical activity may be a low-cost, non-invasive alternative therapy for nvAMD.

Finally, we discovered that the commercially available and widely used RF/6A cell line, described as ‘chorioretinal endothelial’ cells, exhibits no characteristics of endothelial cells through anatomical, transcriptional, and functional assays. This study underscores the importance of verifying not only the identity of cells used but also the validity of experimental models used in the laboratory.

Collectively, the work here not only reconciles previously disparate observations of the role of inflammasomes in modulating aberrant ocular angiogenesis but also improves the investigational repertoire for those who wish to expand their experimental techniques in identifying potential causes and treatments for pathological angiogenesis.