miR15a regulates NLRP3 inflammasome proteins in the retinal vasculature.

We have previously published that miR15a can reduce inflammatory cytokines, which could be key to diabetic retinal pathology. In this work, we wanted to investigate whether miR15a altered NLR pyrin domain 3 (NLRP3) proteins. Whole retinal lysates from both miR15a overexpressing mice and endothelial cell specific miR15a/16 knockout mice were used to investigate protein levels of forkhead box protein O1 (Foxo1), NLRP3, cleaved caspase 1 and interleukin-1 beta (IL-1β). Primary human retinal endothelial cells (REC) were cultured in normal and high glucose followed by transfection with a miR15a mimic for protein analyses. miR15a expression was verified by quantitative PCR, and a luciferase binding assay was used to examine whether miR15a directly bound Foxo1. In mouse retinal lysates, loss of miR15a increased Foxo1, IL-1β, NLRP3, and cleaved caspase 1 levels. REC grown in high glucose transfected with the miR15a mimic had decreased levels of Foxo1 and NLRP3. miR15a directly binds to Foxo1. miR15a regulates NLRP3 actions in the retinal vasculature. Work in mice showed that loss of miR15a increased NLRP3 pathway signaling and Foxo1. miR15a mimics decreased levels of Foxo1 and NLRP3. Taken together, miR15a reduced inflammasome proteins and Foxo1 levels in the retinal vasculature.