Abstract 11698: Pulmonary Hypertension in S100A1 KO Mice is Associated With Endothelial Cell Dysfunction and Impaired eNOS Activation Dependent in Part on the Receptor for Advanced Glycation End-Products (RAGE)
Background: S100A1, a 10-kDa, Ca 2+- binding protein is expressed in endothelial cells and its absence is associated with impaired production of nitric oxide (NO) and mild systemic hypertension. As endothelial dysfunction contributes to clinical and experimental pulmonary hypertension (PH), we investigated the impact of deleting S100A1 in knockout mice (KO) on pulmonary hemodynamic and endothelial function.
Methods and Results: Under basal conditions in vivo, S100A1 deficient mice exhibited a significant elevation in right ventricular systolic pressure (28.41±3.6 vs.14.9±2.41 mmHg in wild-type (WT), p< 0.05, n=6) accompanied by increase in right ventricle hyperthrophy (0.92±0.04 vs.0.79±0.03 in WT. p< 0.05, n=12), increase percentage of wall thickness of pulmonary arteries (12.98±3.34 vs.4.16 ± 1.63 in WT, p< 0.05, n=4 mice per group), and a reduction in microvascular perfusion determined by fluorescent microangiography. In isolated lung preparations, compared to WT, KO revealed reduced basal NO production measured by real-time imaging of fluorescent NO-sensitive dye DAF-FM, blunted dose-responsiveness to acetylcholine, (Ach,10-4 M increased fluorescence 1.43±0.31-fold vs. 3.91±0.43-fold in WT, p<0.05, n=5) and augmented basal and angiotensin (AII)-induced pulmonary vascular resistance. S100A1 protein delivery prevents increase pulmonary arterial pressure and vascular resistance in isolated perfused lung from KO mice. Phosphorylation of endothelial nitric oxide synthase (eNOS) at the stimulatory residue, Ser1177, by exogenous S100A1 treatment (100nM, 30 min) was 2.19- fold greater in WT vs. KO (p<0.05, n=5). This effect was attenuated by pre- incubation with blocking antibodies for RAGE, (166μg/ml), and in the cells isolated from RAGE KO mice, confirming a receptor mediated effect. Moreover, immunofluorescence and co-immunoprecipitation demonstrated heterodimerization of S100A1 with RAGE in ECs and lungs.
Conclusion: Absence of S100A1 results in PH by disrupting its normal capacity to enhance pulmonary endothelial cell function by induction of eNOS activity and NO levels. The ability of exogenously administered S100A1 to rescue this phenotype mediated by RAGE represents a possible therapeutic target in the treatment of PH.
- Pulmonary hypertension
- Nitric oxide synthase
- Receptor-mediated signaling
- Endothelial function
- Nitric oxide
Author Disclosures: K. Teichert-Kuliszewska: None. J. Desjardins: None. W.M. Kuebler: None. T.G. Parker: None.
- © 2014 by American Heart Association, Inc.