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Mediators of Inflammation
Volume 2017 (2017), Article ID 2860956, 7 pages
Research Article

Epac1 Blocks NLRP3 Inflammasome to Reduce IL-1β in Retinal Endothelial Cells and Mouse Retinal Vasculature

1Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, USA
2Department of Ophthalmology, Wayne State University School of Medicine, Detroit, MI, USA

Correspondence should be addressed to Jena J. Steinle

Received 1 November 2016; Revised 24 January 2017; Accepted 5 February 2017; Published 28 February 2017

Academic Editor: Ulrich Eisel

Copyright © 2017 Youde Jiang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Inflammation is an important component of diabetic retinal damage. We previously reported that a novel β-adrenergic receptor agonist, Compound 49b, reduced Toll-like receptor 4 (TLR4) signaling in retinal endothelial cells (REC) grown in high glucose. Others reported that TLR4 activates high-mobility group box 1 (HMGB1), which has been associated with the NOD-like receptor 3 (NLRP3) inflammasome. Thus, we hypothesized that Epac1, a downstream mediator of β-adrenergic receptors, would block TLR4/HMGB1-mediated stimulation of the NLRP3 inflammasome, leading to reduced cleavage of caspase-1 and interleukin-1 beta (IL-1β). We generated vascular specific conditional knockout mice for Epac1 and used REC grown in normal and high glucose treated with an Epac1 agonist and/or NLRP3 siRNA. Protein analyses were done for Epac1, TLR4, HMGB1, NLRP3, cleaved caspase-1, and IL-1β. Loss of Epac1 in the mouse retinal vasculature significantly increased all of the inflammatory proteins. Epac1 effectively reduced high glucose-induced increases in TLR4, HMGB1, cleaved caspase-1, and IL-1β in REC. Taken together, the data suggest that Epac1 reduces formation of the NLRP3 inflammasome to reduce inflammatory responses in the retinal vasculature.