Publications by authors named "Natacha Calatayud"

2 Publications

  • Page 1 of 1

Loss of Sirt3 accelerates arterial thrombosis by increasing formation of neutrophil extracellular traps and plasma tissue factor activity.

Cardiovasc Res 2018 07;114(8):1178-1188

Center for Molecular Cardiology, University of Zurich, Wagistrasse 12, 8952 Schlieren, Switzerland.

Aims: Sirtuin 3 (Sirt3) is a mitochondrial, nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase that reduces oxidative stress by activation of superoxide dismutase 2 (SOD2). Oxidative stress enhances arterial thrombosis. This study investigated the effects of genetic Sirt3 deletion on arterial thrombosis in mice in an inflammatory setting and assessed the clinical relevance of these findings in patients with ST-elevation myocardial infarction (STEMI).

Methods And Results: Using a laser-induced carotid thrombosis model with lipopolysaccharide (LPS) challenge, in vivo time to thrombotic occlusion in Sirt3-/- mice (n = 6) was reduced by half compared to Sirt3+/+ wild-type (n = 8, P < 0.01) controls. Ex vivo analyses of whole blood using rotational thromboelastometry revealed accelerated clot formation and increased clot stability in Sirt3-/- compared to wild-type blood. rotational thromboelastometry of cell-depleted plasma showed accelerated clotting initiation in Sirt3-/- mice, whereas overall clot formation and firmness remained unaffected. Ex vivo LPS-induced neutrophil extracellular trap formation was increased in Sirt3-/- bone marrow-derived neutrophils. Plasma tissue factor (TF) levels and activity were elevated in Sirt3-/- mice, whereas plasma levels of other coagulation factors and TF expression in arterial walls remained unchanged. SOD2 expression in bone marrow -derived Sirt3-/- neutrophils was reduced. In STEMI patients, transcriptional levels of Sirt3 and its target SOD2 were lower in CD14+ leukocytes compared with healthy donors (n = 10 each, P < 0.01).

Conclusions: Sirt3 loss-of-function enhances experimental thrombosis in vivo via an increase of neutrophil extracellular traps and elevation of TF suggesting thrombo-protective effects of endogenous Sirt3. Acute coronary thrombosis in STEMI patients is associated with lower expression levels of SIRT3 and SOD2 in CD14+ leukocytes. Therefore, enhancing SIRT3 activity by pan-sirtuin activating NAD+-boosters may provide a novel therapeutic target to prevent or treat thrombotic arterial occlusion in myocardial infarction or stroke.
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July 2018

Mild endothelial dysfunction in Sirt3 knockout mice fed a high-cholesterol diet: protective role of a novel C/EBP-β-dependent feedback regulation of SOD2.

Basic Res Cardiol 2016 May 12;111(3):33. Epub 2016 Apr 12.

Department of Cardiology, University Heart Center Zurich, University Hospital Zurich, Raemistr. 100, 8091, Zurich, Switzerland.

Sirtuin 3 (Sirt3) is an NAD(+)-dependent mitochondrial deacetylase associated with superoxide dismutase 2 (SOD2)-mediated protection from oxidative stress. We have reported accelerated weight gain and impaired metabolic flexibility in atherosclerotic Sirt3 (-/-) mice. Oxidative stress is a hallmark of endothelial dysfunction. Yet, the role of Sirt3 in this context remains unknown. Thus, we aimed to unravel the effects of endogenous Sirt3 on endothelial function and oxidative stress. Knockdown of Sirt3 in human aortic endothelial cells (HAEC) increased intracellular mitochondrial superoxide accumulation, as assessed by electron spin resonance spectroscopy and fluorescence imaging. Endothelium-dependent relaxation of aortic rings from Sirt3 (-/-) mice exposed to a normal diet did not differ from wild-type controls. However, following 12 weeks of high-cholesterol diet and increasing oxidative stress, endothelial function of Sirt3 (-/-) mice was mildly impaired compared with wild-type controls. Relaxation was restored upon enhanced superoxide scavenging using pegylated superoxide dismutase. Knockdown of Sirt3 in cultured HAEC diminished SOD2 specific activity, which was compensated for by a CCAAT/enhancer binding protein beta (C/EBP-β)-dependent transcriptional induction of SOD2. Abrogation of this feedback regulation by simultaneous knockdown of C/EBP-β and Sirt3 exacerbated mitochondrial superoxide accumulation and culminated into endothelial cell death upon prolonged culture. Taken together, Sirt3 deficiency induces a mild, superoxide-dependent endothelial dysfunction in mice fed a high-cholesterol diet. In cultured endothelial cells, a novel C/EBP-β-dependent rescue mechanism maintains net SOD2 activity upon transient knockdown of Sirt3.
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May 2016