We recently discovered that endothelial Nogo-B, a membrane protein of the ER, regulates vascular function by inhibiting the rate-limiting enzyme, serine palmitoyltransferase (SPT), in de novo sphingolipid biosynthesis. Here, we show that endothelium-derived sphingolipids, particularly sphingosine-1-phosphate (S1P), protect the heart from inflammation, fibrosis, and dysfunction following pressure overload and that Nogo-B regulates this paracrine process. SPT activity is upregulated in banded hearts in vivo as well as in TNF-α–activated endothelium in vitro, and loss of Nogo removes the brake on SPT, increasing local S1P production. Hence, mice lacking Nogo-B, systemically or specifically in the endothelium, are resistant to the onset of pathological cardiac hypertrophy. Furthermore, pharmacological inhibition of SPT with myriocin restores permeability, inflammation, and heart dysfunction in Nogo-A/B–deficient mice to WT levels, whereas SEW2871, an S1P1 receptor agonist, prevents myocardial permeability, inflammation, and dysfunction in WT banded mice. Our study identifies a critical role of endothelial sphingolipid biosynthesis and its regulation by Nogo-B in the development of pathological cardiac hypertrophy and proposes a potential therapeutic target for the attenuation or reversal of this clinical condition.

The objective of this study was to evaluate the role of retinoic acid in experimental postinfarction myocardial remodeling. Wistar rats were subjected to myocardial infarction (MI) and treated with retinoic acid (RA), 0.3 mg/(kg x d) (MI-RA, n = 29), or fed a control diet (MI, n = 34). After 6 mo, the surviving rats (MI-RA = 18 and MI = 22) underwent echocardiograms, and isolated hearts were tested for function in vitro. The cross-sectional area of the myocyte (CSA) and interstitial collagen fraction (IC) were measured in a cross section of the heart stained by hematoxylin-eosin and picrosirius red, respectively. The CSA was smaller in the MI-RA group [229 (220,234) microm2] [medians (lower quartile, upper quartile)] than in the MI group [238 (232,241) microm2] (P = 0.01) and IC was smaller in the MI-RA group [2.4 (1.7, 3.1)%] than in the MI group [3.5 (2.6, 3.9)%] (P = 0.05). The infarct size did not differ between the groups [MI = 44.6 (40.8, 48.4)%, MI-RA = 45 (38.6, 47.2)%]. Maximum rate of rise of left ventricular pressure (+dp/dt) was greater in the MI-RA group (2645 +/- 886 mm Hg/s) than in the MI group (2081 +/- 617 mm Hg/s) (P = 0.05). The other variables tested did not differ between groups. Retinoic acid supplementation of rats for 6 mo attenuates the ventricular remodeling process after MI.

Background/Aims: The role of tissue vitamin-A insufficiency on post-infarction ventricular remodeling is unknown. We tested the hypothesis that cardiac vitamin A insufficiency on post-infarction is associated with adverse myocardial remodeling. Methods: After infarction, rats were allocated into two groups: C (controls, n=25); VA (dietary vitamin A restriction, n= 26). After 3 months, the animals were submitted to echocardiogram, morphometric and biochemical analysis. Results: Rats fed the vitamin-A-deficient diet had lower heart and liver retinol concentration and normal plasma retinol. There were no differences in infarct size between the groups. VA showed higher diastolic left ventricular area normalised by body weight (C= 1.81 ± 0.4 cm2/kg, VA= 2.15 ± 0.3 cm2/ kg; p=0.03), left ventricular diameter (C= 9.4 ± 1.4 mm, VA= 10.5 ± 1.2 mm; p=0.04), but similar systolic ventricular fractional area change (C= 33.0 ± 10.0 %, VA= 32.1 ± 8.7 %; p=0.82). VA showed decreased isovolumetric relaxation time normalised by heart rate (C= 68.8 ± 11.4 ms, VA= 56.3 ± 16.8 ms; p=0.04). VA showed higher interstitial collagen fraction (C= 2.8 ± 0.9 %, VA= 3.7 ± 1.1 %; p=0.05). There were no differences in myosin heavy chain expression, metalloproteinase 2 and 9 activation, or IFN-γ and TNF-α cardiac levels. Conclusion: Local tissue vitamin A insufficiency intensified ventricular remodeling after MI, worsening diastolic dysfunction.

The objective of this study was to evaluate the influence of tomato or lycopene supplementation on cardiac remodeling after myocardial infarction (MI). Male Wistar rats were assigned to four groups: the sham group (animals that underwent simulated surgery) that received a standard chow (S; n=18), the infarcted group that received a standard chow (MI; n=13), the infarcted group supplemented with lycopene (1 mg of lycopene/kg body weight/day) (MIL; n=16) and the infarcted group supplemented with tomato (MIT; n=16). After 3 months, morphological, functional and biochemical analyses were performed. The groups MIL and MIT showed decreased interstitial fibrosis induced by infarction. Tomato supplementation attenuated the hypertrophy induced by MI. In addition, tomato and lycopene improved diastolic dysfunction evaluated by echocardiographic and isolated heart studies, respectively. The MI group showed higher levels of cardiac TNF-α compared to the MIL and MIT groups. Decreased nuclear factor E2-related factor 2 was measured in the MIL group. Lipid hydroperoxide levels were higher in the infarcted groups; however, the MIT group had a lower concentration than did the MI group [S=223±20.8, MI=298±19.5, MIL=277±26.6, MIT=261±28.8 (nmol/g); n=8; P<.001]. We also examined left ventricle miRNA expression; when compared to the S group, the MIL group uniquely down-regulated the expression of eight miRNAs. No miRNA was found to be up-regulated uniquely in the MIT and MIL groups. In conclusion, tomato or lycopene supplementation attenuated the cardiac remodeling process and improved diastolic function after MI. However, the effect of lycopene and tomato supplementation occurred through different mechanistic pathways.

Background: Recent studies have assessed the direct effects of smoking on cardiac remodeling and function. However, the mechanisms of these alterations remain unknown. The aim of this study was to investigate de role of cardiac NADPH oxidase and antioxidant enzyme system on ventricular remodeling induced by tobacco smoke. Methods: Male Wistar rats that weighed 200-230 g were divided into a control group (C) and an experimental group that was exposed to tobacco smoke for a period of two months (ETS). After the two-month exposure period, morphological, biochemical and functional analyses were performed. Results: The myocyte cross-sectional area and left ventricle end-diastolic dimension was increased 16.2% and 33.7%, respectively, in the ETS group. The interstitial collagen volume fraction was also higher in ETS group compared to the controls. In addition to these morphological changes, the ejection fraction and fractional shortening were decreased in the ETS group. Importantly, these alterations were related to augmented heart oxidative stress, which was characterized by an increase in NADPH oxidase activity, increased levels of lipid hydroperoxide and depletion of antioxidant enzymes (e.g., catalase, superoxide dismutase and glutathione peroxidase). In addition, cardiac levels of IFN-γ, TNF-α and IL-10 were not different between the groups. Conclusion: Cardiac alterations that are induced by smoking are associated with increased NADPH oxidase activity, suggesting that this pathway plays a role in the ventricular remodeling induced by exposure to tobacco smoke.