A diet rich in unsaturated fatty acids prevents progression toward heart failure in a rabbit model of pressure and volume overload

Background-During heart failure (HF), cardiac metabolic substrate preference changes from fatty acid (FA) toward glucose oxidation. This change may cause progression toward heart failure. We hypothesize that a diet rich in FAs may prevent this process, and that dietary 3-FAs have an added antiarrhythmic effect based on action potential (AP) shortening in animals with HF. Methods and Results-Rabbits were fed a diet containing 1.25% (w/w) high oleic sunflower oil (HF-9, N 11), 1.25% fish oil (HF-3, N11), or no supplement (HF-control, N8). Subsequently, HF was induced by volume and pressure overload. After 4 months, HF-parameters were assessed, electrocardiograms were recorded, and blood and ventricular tissue were collected. Myocytes were isolated for patch clamp or intracellular Ca2-recordings to study electrophysiologic remodeling and arrhythmogenesis. Both the HF-9 and the HF-3 groups had larger myocardial FA oxidation capacity than HF control. The HF-3 group had significantly lower mean ( SEM) relative heart and lung weight (3.3-0.13 and 3.2-0.12 g kg 1, respectively) than HF control (4.8-0.30 and 4.5-0.23), and shorter QTc intervals (167-2.6 versus 182-6.4). The HF-9 also displayed a significantly reduced relative heart weight (3.6-0.26), but had similar QTc (179-4.3) compared with HF control. AP duration in the HF-3 group was 20% shorter due to increased Ito1 and IK1 and triggered activity, and Ca2-aftertransients were less than in the HF-9 group. Conclusions-Dietary unsaturated FAs started prior to induction of HF prevent hypertrophy and HF. In addition, fish oil FAs prevent HF-induced electrophysiologic remodeling and arrhythmias. © 2012 American Heart Association, Inc

Cartilage intermediate layer protein 1 (CILP1): a novel mediator of cardiac extracellular matrix remodelling

Heart failure is accompanied by extracellular matrix (ECM) remodelling, often leading to cardiac fibrosis. In the present study we explored the significance of cartilage intermediate layer protein 1 (CILP1) as a novel mediator of cardiac ECM remodelling. Whole genome transcriptional analysis of human cardiac tissue samples revealed a strong association of CILP1 with many structural (e.g. COL1A2 r2¿=¿0.83) and non-structural (e.g. TGFB3 r2¿=¿0.75) ECM proteins. Gene enrichment analysis further underscored the involvement of CILP1 in human cardiac ECM remodelling and TGFß signalling. Myocardial CILP1 protein levels were significantly elevated in human infarct tissue and in aortic valve stenosis patients. CILP1 mRNA levels markedly increased in mouse heart after myocardial infarction, transverse aortic constriction, and angiotensin II treatment. Cardiac fibroblasts were found to be the primary source of cardiac CILP1 expression. Recombinant CILP1 inhibited TGFß-induced ¿SMA gene and protein expression in cardiac fibroblasts. In addition, CILP1 overexpression in HEK293 cells strongly (5-fold p¿<¿0.05) inhibited TGFß signalling activity. In conclusion, our study identifies CILP1 as a new cardiac matricellular protein interfering with pro-fibrotic TGFß signalling, and as a novel sensitive marker for cardiac fibrosis

Hypoxia induces dilated cardiomyopathy in the chick embryo: mechanism, intervention, and long-term consequences

Background: Intrauterine growth restriction is associated with an increased future risk for developing cardiovascular diseases. Hypoxia in utero is a common clinical cause of fetal growth restriction. We have previously shown that chronic hypoxia alters cardiovascular development in chick embryos. The aim of this study was to further characterize cardiac disease in hypoxic chick embryos. Methods: Chick embryos were exposed to hypoxia and cardiac structure was examined by histological methods one day prior to hatching (E20) and at adulthood. Cardiac function was assessed in vivo by echocardiography and ex vivo by contractility measurements in isolated heart muscle bundles and isolated cardiomyocytes. Chick embryos were exposed to vascular endothelial growth factor (VEGF) and its scavenger soluble VEGF receptor-1 (sFlt-1) to investigate the potential role of this hypoxia-regulated cytokine. Principal Findings: Growth restricted hypoxic chick embryos showed cardiomyopathy as evidenced by left ventricular (LV) dilatation, reduced ventricular wall mass and increased apoptosis. Hypoxic hearts displayed pump dysfunction with decreased LV ejection fractions, accompanied by signs of diastolic dysfunction. Cardiomyopathy caused by hypoxia persisted into adulthood. Hypoxic embryonic hearts showed increases in VEGF expression. Systemic administration of rhVEGF165 to normoxic chick embryos resulted in LV dilatation and a dose-dependent loss of LV wall mass. Lowering VEGF levels in hypoxic embryonic chick hearts by systemic administration of sFlt-1 yielded an almost complete normalization of the phenotype. Conclusions/Significance: Our data show that hypoxia causes a decreased cardiac performance and cardiomyopathy in chick embryos, involving a significant VEGF-mediated component. This cardiomyopathy persists into adulthood

Multiple common comorbidities produce left ventricular diastolic dysfunction associated with coronary microvascular dysfunction, oxidative stress, and myocardial stiffening

Aims More than 50% of patients with heart failure have preserved ejection fraction characterized by diastolic dysfunction. The prevalance of diastolic dysfunction is higher in females and associates with multiple comorbidities such as hypertension (HT), obesity, hypercholesterolemia (HC), and diabetes mellitus (DM). Although its pathophysiology remains incompletely understood, it has been proposed that these comorbidities induce systemic inflammation, coronary microvascular dysfunction, and oxidative stress, leading to myocardial fibrosis, myocyte stiffening and, ultimately, diastolic dysfunction. Here, we tested this hypothesis in a swine model chronically exposed to three common comorbidities. Methods and results DM (induced by streptozotocin), HC (produced by high fat diet), and HT (resulting from renal artery embolization), were produced in 10 female swine, which were followed for 6 months. Eight female healthy swine on normal pig-chow served as controls. The DM + HC + HT group showed hyperglycemia, HC, hypertriglyceridemia, renal dysfunction and HT, which were associated with systemic inflammation. Myocardial superoxide production was markedly increased, due to increased NOX activity and eNOS uncoupling, and associated with reduced NO production, and impaired coronary small artery endothelium-dependent vasodilation. These abnormalities were accompanied by increased myocardial collagen content, reduced capillary/fiber ratio, and elevated passive cardiomyocyte stiffness, resulting in an increased left ventricular end-diastolic stiffness (measured by pressure-volume catheter) and a trend towards a reduced E/A ratio (measured by cardiac MRI), while ejection fraction was maintained. Conclusions The combination of three common comorbidities leads to systemic inflammation, myocardial oxidative stress, and coronary microvascular dysfunction, which associate with myocardial stiffening and LV diastolic dysfunction with preserved ejection fraction

LDL Receptor Knock-Out Mice Are a Physiological Model Particularly Vulnerable to Study the Onset of Inflammation in Non-Alcoholic Fatty Liver Disease

Non-alcoholic steatohepatitis (NASH) involves steatosis combined with inflammation, which can progress into fibrosis and cirrhosis. Exploring the molecular mechanisms of NASH is highly dependent on the availability of animal models. Currently, the most commonly used animal models for NASH imitate particularly late stages of human disease. Thus, there is a need for an animal model that can be used for investigating the factors that potentiate the inflammatory response within NASH. We have previously shown that 7-day high-fat-high-cholesterol (HFC) feeding induces steatosis and inflammation in both APOE2ki and Ldlr(-/-) mice. However, it is not known whether the early inflammatory response observed in these mice will sustain over time and lead to liver damage. We hypothesized that the inflammatory response in both models is sufficient to induce liver damage over time.APOE2ki and Ldlr(-/-) mice were fed a chow or HFC diet for 3 months. C57Bl6/J mice were used as control.Surprisingly, hepatic inflammation was abolished in APOE2ki mice, while it was sustained in Ldlr(-/-) mice. In addition, increased apoptosis and hepatic fibrosis was only demonstrated in Ldlr(-/-) mice. Finally, bone-marrow-derived-macrophages of Ldlr(-/-) mice showed an increased inflammatory response after oxidized LDL (oxLDL) loading compared to APOE2ki mice.Ldlr(-/-) mice, but not APOE2ki mice, developed sustained hepatic inflammation and liver damage upon long term HFC feeding due to increased sensitivity for oxLDL uptake. Therefore, the Ldlr(-/-) mice are a promising physiological model particularly vulnerable for investigating the onset of hepatic inflammation in non-alcoholic steatohepatitis

Allele-Specific Knockdown of ALS-Associated Mutant TDP-43 in Neural Stem Cells Derived from Induced Pluripotent Stem Cells

TDP-43 is found in cytoplasmic inclusions in 95% of amyotrophic lateral sclerosis (ALS) and 60% of frontotemporal lobar degeneration (FTLD). Approximately 4% of familial ALS is caused by mutations in TDP-43. The majority of these mutations are found in the glycine-rich domain, including the variant M337V, which is one of the most common mutations in TDP-43. In order to investigate the use of allele-specific RNA interference (RNAi) as a potential therapeutic tool, we designed and screened a set of siRNAs that specifically target TDP-43(M337V) mutation. Two siRNA specifically silenced the M337V mutation in HEK293T cells transfected with GFP-TDP-43(wt) or GFP-TDP-43(M337V) or TDP-43 C-terminal fragments counterparts. C-terminal TDP-43 transfected cells show an increase of cytosolic inclusions, which are decreased after allele-specific siRNA in M337V cells. We then investigated the effects of one of these allele-specific siRNAs in induced pluripotent stem cells (iPSCs) derived from an ALS patient carrying the M337V mutation. These lines showed a two-fold increase in cytosolic TDP-43 compared to the control. Following transfection with the allele-specific siRNA, cytosolic TDP-43 was reduced by 30% compared to cells transfected with a scrambled siRNA. We conclude that RNA interference can be used to selectively target the TDP-43(M337V) allele in mammalian and patient cells, thus demonstrating the potential for using RNA interference as a therapeutic tool for ALS

Ancient craft gets new life

Disturbances in coronary microcirculatory function, such as the endothelial glycocalyx, are early hallmarks in the development of obesity and insulin resistance. Accordingly, in the present study myocardial microcirculatory perfusion during rest and stress was assessed following metformin or sulodexide therapy in a rat model of diet-induced obesity. Additionally, the effect of degradation of the glycocalyx on myocardial perfusion was assessed in chow-fed rats. Rats were fed a high fat diet (HFD) for 8 weeks and were divided into a group without therapy, and groups that received the anti-diabetic drug metformin or the glycocalyx-stabilizing drug sulodexide in their drinking water during the last 4 weeks of the feeding period. Myocardial microvascular perfusion was determined using first-pass perfusion MRI before and after adenosine infusion. The effect of HFD on microcirculatory properties was also assessed by sidestream darkfield (SDF) imaging of the gastrocnemius muscle. In an acute experimental setting, hyaluronidase was administered to chow-fed control rats to determine the effect of enzymatical degradation of the glycocalyx on myocardial perfusion. HFD-rats developed central obesity and insulin sensitivity was reduced as evidenced by the marked reduction in insulin-induced phosphorylation of Akt in both cardiac and gastrocnemius muscle. We confirmed our earlier findings that the robust increase in myocardial perfusion in chow-fed rats after an adenosine challenge (+56%, p = 0.002) is blunted in HFD rats (+8%, p = 0.68). In contrast, 4-weeks treatment with metformin or sulodexide partly restored the increase in myocardial perfusion during adenosine infusion in HFD rats (+81%, p = 0.002 and +37%, p = 0.02, respectively). Treating chow-fed rats acutely with hyaluronidase, to enzymatically degrade the glyocalyx, completely blunted the increase in myocardial perfusion during stress. In early stages of HFD-induced insulin resistance myocardial perfusion becomes compromised, a process that can be countered by treatment with both metformin and sulodexide. The adverse effect of acute glycocalyx degradation and protective effect of long-term sulodexide administration on myocardial perfusion provides indirect evidence, suggesting a role for the glycocalyx in preserving coronary microvascular function in pre-diabetic animal

Correction to: Metformin and sulodexide restore cardiac microvascular perfusion capacity in diet‑induced obese rats

Following publication of the original article [1], the authors regret errors in Figs. 2b–d. In these figures the images of the representative Akt and phospho-Akt (pAkt) signals should be replaced with the appropriate images. The representative images shown here are correct. The changes do not affect the scientific conclusion and significance of the article