elastin and Ventricular-Dysfunction--Left

WBS is a rare disorder caused by mutations in the chromosomal sub-band 7q11.23 involving the elastin gene. The clinical features (craniofacial, developmental, and cardiovascular abnormalities) are variable. The association with cardiac anomalies is a well-recognized feature, and SVAS is the most common cardiac defect found. End-stage ischemic heart disease is unusual in this setting but when it occurs, OHT remains the final therapeutic option. This decision can be difficult to determine, and it must be tailored to the individual patient based on the clinical status and concomitant cardiovascular and multisystem lesions. To date, no cases of OHT in patients with WBS have been described. We present a 14-month-old patient with WBS who developed severe LV dysfunction secondary to ischemia following a complex staged surgery for SVAS repair. He underwent successful OHT with no post-operative complications, and at three-month follow-up, he remains asymptomatic on standard immunosuppressive therapy. This case constitutes the first demonstration that OHT may be indicated for extended survival in selected children with WBS and we discuss the basic principles for extending the indication for OHT to this scenario as well as the particularities for post-transplant care.

Topics: Cardiac Catheterization; Chromosomes, Human, Pair 7; Elastin; Heart Defects, Congenital; Heart Failure; Heart Transplantation; Hemodynamics; Humans; Hypothyroidism; Immunosuppressive Agents; Infant; Ischemia; Magnetic Resonance Imaging; Male; Treatment Outcome; Ventricular Dysfunction, Left; Williams Syndrome

There is a need for animal models of plaque rupture. We previously reported that elastin fragmentation, due to a mutation (C1039G(+/-)) in the fibrillin-1 (Fbn1) gene, promotes atherogenesis and a highly unstable plaque phenotype in apolipoprotein E deficient (ApoE(-/-)) mice on a Western-type diet (WD). Here, we investigated whether plaque rupture occurred in ApoE(-/-)Fbn1(C1039G+/-) mice and was associated with myocardial infarction, stroke, and sudden death.. Female ApoE(-/-)Fbn1(C1039G+/-) and ApoE(-/-) mice were fed a WD for up to 35 weeks. Compared to ApoE(-/-) mice, plaques of ApoE(-/-)Fbn1(C1039G+/-) mice showed a threefold increase in necrotic core size, augmented T-cell infiltration, a decreased collagen I content (70 ± 10%), extensive neovascularization, intraplaque haemorrhage, and a significant increase in matrix metalloproteinase-2, -9, -12, and -13 expression or activity. Plaque rupture was observed in 70% of ascending aortas and in 50% of brachiocephalic arteries of ApoE(-/-)Fbn1(C1039G+/-) mice. In ApoE(-/-) mice, plaque rupture was not seen in ascending aortas and only in 10% of brachiocephalic arteries. Seventy percent of ApoE(-/-)Fbn1(C1039G+/-) mice died suddenly, whereas all ApoE(-/-) mice survived. ApoE(-/-)Fbn1(C1039G+/-) mice showed coronary plaques and myocardial infarction (75% of mice). Furthermore, they displayed head tilt, disorientation, and motor disturbances (66% of cases), disturbed cerebral blood flow (73% of cases; MR angiograms) and brain hypoxia (64% of cases), indicative of stroke.. Elastin fragmentation plays a key role in plaque destabilization and rupture. ApoE(-/-)Fbn1(C1039G+/-) mice represent a unique model of acute plaque rupture with human-like complications.

Topics: Animals; Aorta; Apolipoproteins E; Biomarkers; Brachiocephalic Trunk; Cardiomegaly; Carotid Artery, Common; Cerebrovascular Circulation; Death, Sudden; Diet, Western; Disease Models, Animal; Elastin; Female; Fibrillin-1; Fibrillins; Hemorrhage; Hypoxia, Brain; Mice; Microfilament Proteins; Microvessels; Myocardial Infarction; Neovascularization, Pathologic; Nervous System Diseases; Plaque, Atherosclerotic; Rupture, Spontaneous; Stroke; Ventricular Dysfunction, Left

Preterm infants are at high risk for long-term abnormalities in cardiopulmonary function. Our objectives were to determine the long-term effects of hypoxia or hyperoxia on cardiopulmonary development and function in an immature animal model. Newborn C57BL/6 mice were exposed to air, hypoxia (12% oxygen), or hyperoxia (85% oxygen) from Postnatal Day 2-14, and then returned to air for 10 weeks (n = 2 litters per condition; > 10/group). Echocardiography, blood pressure, lung function, and lung development were evaluated at 12-14 weeks of age. Lungs from hyperoxia- or hypoxia-exposed mice were larger and more compliant (compliance: air, 0.034 ± 0.001 ml/cm H2O; hypoxia, 0.049 ± 0.002 ml/cm H2O; hyperoxia, 0.053 ± 0.002 ml/cm H2O; P < 0.001 air versus others). Increased airway reactivity, reduced bronchial M2 receptor staining, and increased bronchial α-smooth muscle actin content were noted in hyperoxia-exposed mice (maximal total lung resistance with methacholine: air, 1.89 ± 0.17 cm H2O ⋅ s/ml; hypoxia, 1.52 ± 0.34 cm H2O ⋅ s/ml; hyperoxia, 4.19 ± 0.77 cm H2O ⋅ s/ml; P < 0.004 air versus hyperoxia). Hyperoxia- or hypoxia-exposed mice had larger and fewer alveoli (mean linear intercept: air, 40.2 ± 0. 0.8 μm; hypoxia, 76.4 ± 2.4 μm; hyperoxia, 95.6 ± 4.6 μm; P < 0.001 air versus others; radial alveolar count [n]: air, 11.1 ± 0.4; hypoxia, 5.7 ± 0.3; hyperoxia, 5.6 ± 0.3; P < 0.001 air versus others). Hyperoxia-exposed adult mice had left ventricular dysfunction without systemic hypertension. In conclusion, exposure of newborn mice to hyperoxia or hypoxia leads to cardiopulmonary abnormalities in adult life, similar to that described in ex-preterm infants. This animal model may help to identify underlying mechanisms and to develop therapeutic strategies for pulmonary morbidity in former preterm infants.

Topics: Actins; Age Factors; Animals; Animals, Newborn; Blood Pressure; Bronchial Hyperreactivity; Bronchoconstriction; Cardiovascular System; Collagen; Disease Models, Animal; Elastin; Hyperoxia; Hypoxia; Lung; Lung Compliance; Mice, Inbred C57BL; Receptor, Muscarinic M2; Time Factors; Ventricular Dysfunction, Left; Ventricular Function, Left

Despite extensive strides in understanding pressure overload induced heart failure, there is very little known about oxidative stress induced matrix metalloproteinase (MMP) activation, collagen degradation and remodeling in pressure overload heart failure. We hypothesize that pressure overload leads to redox imbalance causing increased expression/activity of MMP-2/9 producing collagen degradation and heart failure. To test this hypothesis, we created pressure overload heart failure by abdominal aortic stenosis (AS) in wild-type C57BL/6J and collagen mutant (Col1a1 with 129 s background) mice. At 4 weeks, post surgery, functional parameters were measured. Left ventricle (LV) tissue sections were analyzed by histology, Western Blot and PCR. The results suggest an increase in iNOS with a decrease in eNOS, an increase in nitrated protein modification and depletion of antioxidants thioredoxin and SOD in pressure overload. MMP-2/9 expression/activity and collagen degradation were increased in the AS animals. To determine whether a mutation in the collagen gene at the site of MMP cleavage mitigates cardiac hypertrophy, we used Col1a1 mice. In these mice, the AS induced LV hypertrophy (LVH) was ameliorated. In conclusion, our results suggest that AS leads to increased oxidative stress, expression/activity of MMP-2/9 and a decrease in antioxidant expression producing collagen degradation and heart failure.

Topics: Analysis of Variance; Animals; Aortic Valve Stenosis; Blood Pressure; Blotting, Western; Chronic Disease; Collagen; Disease Models, Animal; Echocardiography; Elastin; Electrocardiography; Enzyme Activation; Heart Failure; Hypertrophy, Left Ventricular; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Oxidative Stress; Research Design; Reverse Transcriptase Polymerase Chain Reaction; Stroke Volume; Ventricular Dysfunction, Left