Abstract 18210: Acetylated Proline-Glycine-Proline Couples Extracellular Matrix Fragmentation to Increased Vascular Endothelin-1 Production in Heart Transplant Patients
Introduction: The endothelium is a critical regulator of vascular function, and alterations in the production of nitric oxide (NO) and endothelin-1 (ET1) are known to correlate with cardiovascular disease. Acetylated Proline-Glycine-Proline (AcPGP), a pro-inflammatory matrix-derived cytokine (matrikine), has recently been demonstrated to couple extracellular matrix (ECM) fragmentation to increased endothelial permeability. However, the impact of ECM damage and fragmentation in regulating endothelial function remains unknown. Herein, we report AcPGP to be a potent stimulator of ET1 both in vitro and in a cohort of heart transplant (HTx) patients.
Methods: Coronary serum from HTx patients was collected during angiographic screening for transplant vasculopathy (N=7). Serum AcPGP was measured by mass spectroscopy. In vitro experiments employed human aortic endothelial cells cultured in a microfluidic cell culture model with both laminar and disturbed flow. Cells were treated with either AcPGP or control peptide Proline-Glycine-Glycine (PGG) for 48hours (250μg/mL). Static endothelial cell culture experiments were also conducted. An ET1 ELISA kit (R&D Systems) was used to measure ET1 concentrations. NO concentrations were measured by a chemiluminescence assay. Protein expression of Endothelin Converting Enzyme 1 (ECE1) was determined by western blot analysis.
Results: Compared to PGG, AcPGP in the endothelial flow model induced a 2.7 fold increase in ET1 production (14.7 ± 2.8 versus 40 ± 8.5 pg/mL, P < 0.05). AcPGP in static endothelial cell culture also increased ET1 production in a dose-dependent manner within 24hours (0.1 – 1.0mg/mL, P < 0.05 vs. control). No differences in endothelial cell NO production or ECE1 expression were observed. Clinically, ET1 linearly correlated with serum AcPGP concentrations from coronary samples (R2 = 0.8, P = 0.01).
Conclusions: The results identify AcPGP as a novel matrikine capable of increasing vascular ET1, and highlight its potential role as a paracrine regulator of vascular function and inflammation. Importantly, these results are the first to link ECM fragmentation with an established mediator of cardiovascular disease in HTx patients.
Author Disclosures: G.A. Payne: None. J. Li: None. X. Xu: None. P. Jackson: None. J. Wells: None. S. Oparil: None. M. Leesar: None. P. Sethu: None. R.P. Patel: None. J. Blalock: None. A. Gaggar: None.
- © 2016 by American Heart Association, Inc.