Abstract 20097: Shear-Sensitive Lipid Phosphate Phosphatase 3 Maintains Nitric Oxide-Mediated Flow-Induced Dilation In Healthy Human Arterioles
Shear-stimulated release of nitric oxide (NO) is the most important physiological endothelium-dependent vasodilator response (flow-induced dilation; FID) in the arteriolar circulation. However, in patients with coronary artery disease (CAD), NO bioavailability is reduced and the mediator of FID switches to hydrogen peroxide (H2O2), a pro-inflammatory agent. Interestingly, reduced expression of the shear-sensitive lipid phosphate phosphatase 3 (LPP3) also produces endothelial inflammation, reduction in NO and an increase in H2O2.
Objective: We hypothesize that reduced expression of LPP3 leads to disruption of NO-mediated FID in human adipose arterioles and elicits a switch to H2O2 as the mediator of FID. We propose that restoring expression of LPP3 in patients with CAD restores NO-mediated FID.
Methods: Adipose arterioles isolated from subjects with and without CAD were prepared for videomicroscopy. Decreased expression of LPP3 in healthy vessels was achieved by LPP3-targeted siRNA. Anti-miR92a, an inhibitor of miR92a, which decreases expression of LPP3, was used to increase expression of LPP3 in vessels from CAD patients. RT-qPCR in cultured endothelial cells was used to test the effects of decreased expression of LPP3 on endothelial nitric oxide synthase (eNOS) expression.
Results: In healthy vessels, FID was maintained but NO was no longer involved after siRNA-mediated knockdown of LPP3 (% max dilation: siRNA 74.2±5.62, n=10 vs siRNA+L-NAME [NOS inhibitor; 100μM] 84.8±4.46 n=6). Anti-miR92a restored NO-mediated FID in CAD vessels (anti-miR92a 73.0±4.29, n=6 vs anti-miR92a+L-NAME -6.30±20.6 n=3) while phenylboronic acid (PBA: H2O2 scavenger; 5μM) had no effect (anti-miR92a 73.0±4.29, n=6 vs anti-miR92a+PBA 70.6±8.91, n=3). Knock-down of LPP3 in cultured endothelial cells led to 34% reduction in eNOS mRNA expression (normalized to GAPDH; n=2) in comparison to vehicle control.
Conclusion: Reduced expression of LPP3 leads to disruption of NO-mediated FID in healthy human arterioles, recapitulating the situation in CAD. Inhibition of miR92a, which decreases LPP3 protein expression in vessels from patients with CAD restores NO-mediated dilation. Normal function/expression of LPP3 is necessary to maintain NO-mediated FID.
Author Disclosures: D. Chabowski: None. K. Ait-Aissa: None. A. Kadlec: None. J. Hockenberry: None. A. Beyer: None. D. Gutterman: None.
- © 2016 by American Heart Association, Inc.