title: Epac1 Blocks NLRP3 Inflammasome to Reduce IL-1βin Retinal Endothelial Cells and Mouse Retinal Vasculature.
abstract: Inflammation is an important component of diabetic retinal damage. We previously reported that a novelβ-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 ofβ-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-1βin REC. Taken together, the data suggest that Epac1 reduces formation of the NLRP3 inflammasome to reduce inflammatory responses in the retinal vasculature.
authors.affiliation: Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Youde
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Curtiss
authors.affiliation: Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, USA; Department of Ophthalmology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Jena J
authors.identifier: 0000-0002-7539-2892
authors.initials: JJ
authors.lastname: Steinle
mesh_terms: D000818:Animals; D015153:Blotting, Western; D020170:Caspase 1 / Q000378:metabolism; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology; D020662:Guanine Nucleotide Exchange Factors / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D024243:HMGB1 Protein / Q000235:genetics / Q000378:metabolism; D006801:Humans; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein / Q000235:genetics / Q000378:metabolism*; D012160:Retina / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism
chemical_list: C482601:Epac protein, mouse; D020662:Guanine Nucleotide Exchange Factors; D024243:HMGB1 Protein; D053583:Interleukin-1beta; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C453881:NLRP3 protein, human; D051197:Toll-Like Receptor 4; D020170:Caspase 1; D005947:Glucose