Abstract P3156: Activated Fibroblast-Derived Exosomal Mir-216a-5p Promotes Endothelial Dysfunction By Targeting PGM5 In Diabetic Heart

Abstract

Background: Diabetic patients are more susceptible to heart failure (HF). High blood glucose level in diabetic patients eventually triggers the body's inflammatory response and causes cardiac fibroblast activation, endothelial cell dysfunction (ECD), and, ultimately, HF. Previously, we have shown that activated fibroblast-mediated ECD leads to HF. However, the molecular mechanism of fibroblast-induced ECD in diabetics is not yet well defined. Therefore, we hypothesized that “myofibroblast in the diabetic heart secretes exosomes loaded with antiangiogenic/profibrotic factors, which impair EC function.” Methods: Exosomes were isolated from diabetic mice plasma and fibroblast conditioned media by ultracentrifugation and characterized by nanosight & electron microscopy. We cultured mouse primary heart endothelial cells in EC growth media. ECs were treated with exosomes derived from fibroblasts (treated with either 25mM glucose, 500nM Angiotensin II (AngII) or both) for 48 hr. Mannitol (25mM) served as control. Pathway-based miRNA array was screened with exosome-derived miR, and targets were predicted bioinformatically for selected miR. Results: Glu-AngII cotreatment significantly activated fibroblasts as shown by qPCR (Col1α, and FN expression) and western blot (pSmad2/Smad2, p-p38/p38). Interestingly, exosomes derived from activated fibroblasts significantly induced ECD (eNOS, VEGF, CD31 genes, and proteins expression). We further checked the effect of diabetic mice plasma exosomes on ECs function. We found significantly impaired endothelial function, as shown by Matrigel tube formation and Boyden chamber migration assays. Micro RNA array and qPCR data showed that miR-216a-5p was highly upregulated in exosomes derived from FBs cotreated with Glu-AngII. Pathway-based analysis revealed that PGM5 could be a potential target in miR-216-induced ECD. Interestingly, miR-216a-5p inhibition significantly rescued diabetes-induced PGM5 inhibition and improved endothelial function Conclusions: Taken together, this study demonstrates that fibroblast in the diabetic heart releases miR-216a-5p through exosomes, which promote endothelial dysfunction via the miR-216a-5p/PGM5 axis.