Adult Vascular Dysfunction Research Articles

Adult vascular dysfunction in foetal growth-restricted guinea-pigs is associated with a neonate-adult switching in Nos3 DNA methylation.

Foetal growth restriction (FGR) is associated with endothelial dysfunction and cardiovascular diseases in adult subjects. Early vascular remodelling and epigenetic changes occurring on key endothelial genes might precede this altered vascular function. Further, it has been proposed that oxidative stress during development may determine some of these epigenetic modifications. To address this issue, we studied the in vivo and ex vivo vascular function and Nos3 promoter DNA methylation in arteries from eight-month-old guinea-pig born from control, FGR-treated and FGR-NAC-treated pregnancies. Femoral and carotid arteries in vivo vascular function were determined by Doppler, whilst ex vivo vascular function and biomechanical properties were assessed by wire myography. Levels of eNOS mRNA and site-specific DNA methylation in Nos3 promoter in aorta endothelial cells (AEC) were determined by qPCR and pyrosequencing respectively. FGR adult showed an increased femoral vascular resistance (P<.05), stiffness (P<.05) and arterial remodelling (P<.01), along with an impaired NO-mediated relaxation (P<.001). These effects were prevented by maternal treatment with NAC. Endothelial-NOS mRNA levels were decreased in FGR adult compared with control and FGR-NAC (P<.05), associated with increased DNA methylation levels (P<.01). Comparison of Nos3 DNA methylation in AEC showed a differential methylation pattern between foetal and adult guinea-pigs (P<.05). Altogether, these data suggest that adult vascular dysfunction in the FGR does not result from early changes in Nos3 promoter DNA methylation, but from an altered vessel structure established during foetal development.

Tyrosine phosphorylation of Kv1.5 is upregulated in intrauterine growth retardation rats with exaggerated pulmonary hypertension.

Intrauterine growth retardation (IUGR) is associated with the development of adult-onset diseases, including pulmonary hypertension. However, the underlying mechanism of the early nutritional insult that results in pulmonary vascular dysfunction later in life is not fully understood. Here, we investigated the role of tyrosine phosphorylation of voltage-gated potassium channel 1.5 (Kv1.5) in this prenatal event that results in exaggerated adult vascular dysfunction. A rat model of chronic hypoxia (2 weeks of hypoxia at 12 weeks old) following IUGR was used to investigate the physiological and structural effect of intrauterine malnutrition on the pulmonary artery by evaluating pulmonary artery systolic pressure and vascular diameter in male rats. Kv1.5 expression and tyrosine phosphorylation in pulmonary artery smooth muscle cells (PASMCs) were determined. We found that IUGR increased mean pulmonary artery pressure and resulted in thicker pulmonary artery smooth muscle layer in 14-week-old rats after 2 weeks of hypoxia, while no difference was observed in normoxia groups. In the PASMCs of IUGR-hypoxia rats, Kv1.5 mRNA and protein expression decreased while that of tyrosine-phosphorylated Kv1.5 significantly increased. These results demonstrate that IUGR leads to exaggerated chronic hypoxia pulmonary arterial hypertension (CH-PAH) in association with decreased Kv1.5 expression in PASMCs. This phenomenon may be mediated by increased tyrosine phosphorylation of Kv1.5 in PASMCs and it provides new insight into the prevention and treatment of IUGR-related CH-PAH.

High-salt intake during pregnancy modifies placenta phenotype at least until the third generation

High-salt intake during pregnancy modifies placenta phenotype at least until the third generation

Sex-specific epigenetic impact of preconceptional maternal weight loss on foeto-placental development

Sex-specific epigenetic impact of preconceptional maternal weight loss on foeto-placental development

Abstract 335: Vascular Histone Deacetylase Mediates Early Life Stress-Induced Endothelial Dysfunction

Chromatin remodeling is an important factor in the etiology of vascular pathologies. Also, early life stress (ELS) is linked to increased risk of vascular disease in adults. We used maternal separation with early weaning (MSEW) to study mechanisms of ELS-mediated adult vascular dysfunction in male C57BL/6J mice. Litters were subjected to maternal separation 4h/day (postnatal day (PD) 2-5) and 8h/day (PD6-16), and weaned at PD17. Control (CON) litters were undisturbed until weaning at PD21. Subsequent experiments were performed at 12 weeks old. MSEW blunted aortic ACh-mediated vasorelaxation (MSEW: 68% vs CON: 90%, p=0.01), while SNP-induced vasorelaxation was similar in CON and MSEW aortae. Apocynin (300 μM) and superoxide dismutase (100 U/mL) normalized MSEW-induced endothelial dysfunction. We hypothesize that ELS induces aortic endothelial dysfunction by increasing NADPH oxidase expression and/or decreasing nitric oxide synthase 3 (NOS3) expression. Aortic protein expression of NADPH oxidase subunit p67 was elevated in MSEW mice (45% increase from CON, n=11, p=0.02). NOS3 protein expression and NOS3 serine 1177 phosphorylation was not different between groups, indicating that NOS3 activation by phosphorylation does not contribute to ELS-induced endothelial dysfunction. We further hypothesize that chromatin modification mediates ELS-induced endothelial dysfunction. Aortic mRNA expressions of 84 chromatin modification enzymes (methyltransferases, demethylases, acetyltransferases, deacetylases) were assessed by qRT-PCR. Only histone deacetylase (HDAC) 1, 6 and 9 mRNA levels were significantly upregulated in MSEW aortae compared to CON (17%, 29% and 67% increase, respectively, p&lt;0.05). However, only HDAC 9 protein expression was elevated in MSEW aortae (2 fold increase from CON, n=6, p=0.01). Accordingly, histone 3 lysine acetylation was slightly decreased in MSEW aortae (16% decrease from CON, n=6, p = 0.06). Pretreatment of aortae with an HDAC inhibitor, trichostatin A (TSA), normalized ACh-induced vasorelaxation in MSEW mice (MSEW: 68% vs MSEW + TSA: 88%, p=0.02), while not affecting ACh-induced vasorelaxation in CON mice. We conclude that ELS induces endothelial dysfunction, most likely, through an HDAC 9-mediated pathway.

Abstract 57: Histone Deacetylase Inhibition Attenuates Early Life Stress-Induced Endothelial Dysfunction

Epidemiological studies show that early life stress (ELS) is linked to cardiovascular disease in adulthood. We used a model of maternal separation with early weaning (MSEW) to study the mechanisms of ELS-mediated adult vascular dysfunction in male C57BL/6J mice. MSEW litters were subjected to maternal separation 4h/day (postnatal day (PD) 2 to 5) and 8h/day (PD6 to 16), and weaned at PD17. Control (CON) litters were undisturbed until weaning at PD21. All subsequent experiments were performed in adult mice (12 weeks old). We hypothesized that MSEW increases vascular inflammation and endothelial dysfunction in male mice. Systolic blood pressure (tail-cuff) of MSEW mice was not different from CON mice (109.3 + 10.9 vs 116.7 + 20.8 mmHg, respectively). Circulating soluble intercellular adhesion molecule (CON: 333.5 + 19.4 vs MSEW: 406.2 + 23.1 ng/ml; p = 0.03) and macrophage colony stimulating factor (CON: 737.4 + 19.6 vs MSEW: 945.3 + 65.4 pg/ml; p = 0.01) were elevated by MSEW. Also, aortic adventitial macrophage infiltration was increased in mice exposed to MSEW (F4/80 immunostaining; CON: 2.8 + 2.3 vs MSEW: 7.0 + 2.2 cells/mm 2 ; p = 0.05). We performed wire myography on thoracic aortae to determine vasorelaxation with cumulative concentration-response curve to acetylcholine (ACh; 1 X 10 -9 M to 3 X 10 -5 M) and sodium nitroprusside (SNP; 1 X 10 -10 M to 3 X 10 -5 M). MSEW induced blunted ACh-mediated vasorelaxation (MSEW: 67.6 + 5.8 vs CON: 89.9 + 2.7 % of phenylephrine constriction (% of PE), p = 0.01), while SNP-induced vasorelaxation was similar in CON and MSEW mice. We further hypothesized that MSEW-induced endothelial dysfunction is mediated via increased histone deacetylase (HDAC) expression. Real-time quantitative PCR revealed upregulation of HDAC 1, 6 and 9 in aortae of MSEW mice (1.28 + 0.12, 1.28 + 0.18 and 1.65 + 0.05 fold change from CON, respectively, p &lt; 0.05). Pretreatment with trichostatin A (TSA), an HDAC inhibitor, normalized ACh-induced vasorelaxation in aortae of MSEW mice (MSEW: 67.6 + 5.8 vs MSEW + TSA: 88.44 + 3.2 % of PE, p = 0.02), while not affecting ACh-induced vasorelaxation in aortae from CON mice (CON: 89.9 + 2.7 vs CON + TSA: 90.3 + 4.5 % of PE). We conclude that ELS induces blood pressure-independent endothelial dysfunction through an HDAC-mediated pathway.

Effect of age and COX‐2‐derived prostanoids on the progression of adult vascular dysfunction in the offspring of diabetic rats

The present study was designed to determine how diabetes in pregnancy affects vascular function in their offspring, the influence of age and whether COX activation is involved in this effect. Relaxation responses to ACh were analysed in mesenteric resistance arteries from the offspring of control rats (O-CR) and those of diabetic rats (O-DR) at 3, 6 and 12 months of age. TxB₂, PGE₂ and PGF(2α) release were determined by enzyme immunoassay. COX-1 and COX-2 expression were measured by Western blot analysis. O-DR developed hypertension from 6 months of age compared with O-CR. In O-DR, relaxation responses to ACh were impaired in all ages studied and were restored by COX-2 inhibition. TP receptor blockade (SQ29548) restored ACh relaxation in arteries from 3-month-old O-DR while TP and EP receptor blockade (SQ29548 + AH6809) was required to restore it in 6-month-old O-DR. In 12-month-old O-DR, ACh relaxation was restored when TP, EP and FP receptors were blocked (SQ29548 + AH6809 + AL8810). ACh-stimulated TxB₂ was higher in all O-DR. ACh-stimulated PGE₂ release was increased in arteries from 6- and 12-month-old O-DR, whereas PGF(2α) was increased only in 12-month-old O-DR. COX-2, but not COX-1, expression was higher in O-DR than O-CR. The results indicate an age-dependent up-regulation of COX-2 coupled to an enhanced formation of vasoconstrictor prostanoids in resistance arteries from O-DR. This effect plays a key role in the pathogenesis of endothelial dysfunction, which in turn could contribute to the progression of vascular dysfunction in these rats.

Effect of age and gender on the progression of adult vascular dysfunction in a mouse model of fetal programming lacking endothelial nitric oxide synthase

The objective of this study was to investigate vascular function at different ages in a transgenic murine model of fetal vascular programming using a model of uteroplacental insufficiency induced by lack of endothelial nitric oxide synthase. Homozygous NOS3 knockout (KO) and wild-type (WT) mice were cross bred to produce WT, KO, and heterozygous that developed in WT (KOP) or KO (KOM) mothers. Male/female offspring from the four groups were killed at 7, 14, and 21 wk of age (n = 5-10/group), and carotid arteries were used for in vitro vascular studies. Responses to phenylephrine (PE), with/without N(G)-nitro-L-arginine methyl ester (L-NAME), angiotensin (ANG), acetylcholine (ACh), sodium nitroprusside, and isoproterenol (ISO) were studied. At 7 wk, only KO offspring showed higher contractile response to PE, whereas, at 14 and 21 wk, both KO and KOM had a higher response. Incubation with L-NAME abolished these differences. ANG contraction was higher in male KO in all age groups and in 21-wk-old females. Relaxation to ACh and ISO was absent in KO, and significantly decreased in KOM offspring in all age groups compared with KOP and WT, independent of gender. Sodium nitroprusside was not different between groups. The effect of the altered intrauterine environment on the development of abnormal vascular function was limited at 7 wk of age and most evident at 14 wk; further deterioration was limited to ANG-mediated vascular contractility in KO offspring. Our findings provide some hope that at least the first seven postnatal weeks may be an appropriate therapeutic window to prevent cardiovascular disease later in life.

The role of oxidative and inflammatory stress in the developmental origin of adult vascular dysfunction

Previous studies in endothelial nitric oxide synthase (NOS3) knockout mice showed that vascular function in adult offspring is altered by the adverse intrauterine environment. Oxidative stress and low-grade inflammation play a role in the pathogenesis of adult vascular disease. Our objective was to determine if oxidative stress and low-grade inflammation also play a role in the altered fetal vascular programming.

Fetal origins of adult vascular dysfunction in mice lacking endothelial nitric oxide synthase

Epidemiological studies have shown increased incidence of hypertension and coronary artery disease in growth-restricted fetuses during their adult life. A novel animal model was used to test the hypothesis regarding the role of an abnormal uterine environment in fetal programming of adult vascular dysfunction. Mice lacking a functional endothelial nitric oxide synthase (NOS3-/-KO, where KO is knockout) and wild-type (WT) mice (NOS3+/+WT) were crossbred to produce homozygous NOS3-/-KO, maternally derived heterozygous (NOS3+/-mat, mother with NOS3 deficiency), paternally derived heterozygous (NOS3+/-pat, normal mother), and NOS3+/+WT litters. Number of fetuses per litter was smaller in NOS3-/-KO and NOS3+/-mat compared with NOS3+/-pat and NOS3+/+WT mice. Adult female mice from these litters (7-8 wk old) were killed, and ring preparations of carotid and mesenteric arteries were mounted in a wire myograph to evaluate the passive and reactive vascular characteristics. Slope of the length-tension plot (a measure of vascular compliance) was increased, and optimal diameter (as calculated by Laplace equation) was decreased in NOS3-/-KO and NOS3+/-mat compared with NOS3+/-pat and NOS3+/+WT mice. Acetylcholine caused vasorelaxation in NOS3+/-pat and NOS3+/+WT and contraction in NOS3-/-KO and NOS3+/-mat mice. Responses to phenylephrine and Ca2+ were increased in NOS3-/-KO and NOS3+/-mat compared with NOS3+/-pat and NOS3+/+WT mice. Relaxation to isoproterenol was decreased in NOS3-/-KO and NOS3+/-mat vs. NOS3+/-pat and NOS3+/+WT mice. Abnormalities in the passive and reactive in vitro vascular properties seen in NOS+/-mat that developed in a NOS3-deficient maternal/uterine environment compared with the genetically identical NOS3+/-pat mice that developed in a normal environment are the first direct evidence in support of a role for uterine environment in determining vascular function in later life.