Cardiomyocyte peroxisome proliferator-activated receptor α is essential for energy metabolism and extracellular matrix homeostasis during pressure overload-induced cardiac remodeling.

Peroxisome proliferator-activated receptor α (PPARα), a ligand-activated nuclear receptor critical for systemic lipid homeostasis, has been shown closely related to cardiac remodeling. However, the roles of cardiomyocyte PPARα in pressure overload-induced cardiac remodeling remains unclear because of lacking a cardiomyocyte-specific Ppara-deficient (PparaΔCM) mouse model. This study aimed to determine the specific role of cardiomyocyte PPARα in transverse aortic constriction (TAC)-induced cardiac remodeling using an inducible PparaΔCM mouse model. PparaΔCM and Pparafl/fl mice were randomly subjected to sham or TAC for 2 weeks. Cardiomyocyte PPARα deficiency accelerated TAC-induced cardiac hypertrophy and fibrosis. Transcriptome analysis showed that genes related to fatty acid metabolism were dramatically downregulated, but genes critical for glycolysis were markedly upregulated in PparaΔCM hearts. Moreover, the hypertrophy-related genes, including genes involved in extracellular matrix (ECM) remodeling, cell adhesion, and cell migration, were upregulated in hypertrophic PparaΔCM hearts. Western blot analyses demonstrated an increased HIF1α protein level in hypertrophic PparaΔCM hearts. PET/CT analyses showed an enhanced glucose uptake in hypertrophic PparaΔCM hearts. Bioenergetic analyses further revealed that both basal and maximal oxygen consumption rates and ATP production were significantly increased in hypertrophic Pparafl/fl hearts; however, these increases were markedly blunted in PparaΔCM hearts. In contrast, hypertrophic PparaΔCM hearts exhibited enhanced extracellular acidification rate (ECAR) capacity, as reflected by increased basal ECAR and glycolysis but decreased glycolytic reserve. These results suggest that cardiomyocyte PPARα is crucial for the homeostasis of both energy metabolism and ECM during TAC-induced cardiac remodeling, thus providing new insights into potential therapeutics of cardiac remodeling-related diseases.

Shikonin attenuates hyperhomocysteinemia-induced CD4+ T cell inflammatory activation and atherosclerosis in ApoE-/- mice by metabolic suppression.

T cell metabolic activation plays a crucial role in inflammation of atherosclerosis. Shikonin (SKN), a natural naphthoquinone with anti-inflammatory activity, has shown to exert cardioprotective effects, but the effect of SKN on atherosclerosis is unclear. In addition, SKN was found to inhibit glycolysis via targeting pyruvate kinase muscle isozyme 2 (PKM2). In the present study, we investigated the effects of SKN on hyperhomocysteinemia (HHcy)-accelerated atherosclerosis and T cell inflammatory activation in ApoE-/- mice and the metabolic mechanisms in this process. Drinking water supplemented with Hcy (1.8 g/L) was administered to ApoE-/- mice for 2 weeks and the mice were injected with SKN (1.2 mg/kg, i.p.) or vehicle every 3 days. We showed that SKN treatment markedly attenuated HHcy-accelerated atherosclerosis in ApoE-/- mice and significantly decreased inflammatory activated CD4+ T cells and proinflammatory macrophages in plaques. In splenic CD4+ T cells isolated from HHcy-ApoE-/- mice, SKN treatment significantly inhibited HHcy-stimulated PKM2 activity, interferon-γ secretion and the capacity of these T cells to promote macrophage proinflammatory polarization. SKN treatment significantly inhibited HHcy-stimulated CD4+ T cell glycolysis and oxidative phosphorylation. Metabolic profiling analysis of CD4+ T cells revealed that Hcy administration significantly increased various glucose metabolites as well as lipids and acetyl-CoA carboxylase 1, which were reversed by SKN treatment. In conclusion, our results suggest that SKN is effective to ameliorate atherosclerosis in HHcy-ApoE-/- mice and this is at least partly associated with the inhibition of SKN on CD4+ T cell inflammatory activation via PKM2-dependent metabolic suppression.

DKK3 overexpression attenuates cardiac hypertrophy and fibrosis in an angiotensin-perfused animal model by regulating the ADAM17/ACE2 and GSK-3ß/ß-catenin pathways.

AIMS: Cardiac pressure and humoral factors induce cardiac hypertrophy and fibrosis, which are characterized by increased stiffness, reduced contractility and altered perfusion. Angiotensin II (AngII) is well known to promote this pathology. Angiotensin-converting enzyme (ACE) 2, which cleaves AngII and forms Ang-(1-7), exerts protective anti-hypertrophy and anti-fibrosis effects. A disintegrin and metalloproteinase 17 (ADAM17), a membrane-bound enzyme reported to cleave ACE2, may participate in the pathological process of AngII perfusion-induced heart damage. However, researchers have not clearly determined whether dickkopf-3 (DKK3) regulates the ADAM17/ACE2 pathway and, if so, whether DKK3-mediated regulation is related to the glycogen synthase kinase-3ß (GSK-3ß)/ß-catenin pathway. In this study, we explored whether DKK3 overexpression ameliorates the development of AngII-induced cardiac fibrosis and hypertrophy through the ADAM17/ACE2 and GSK-3ß/ß-catenin pathways. METHODS: Mice were injected with a DKK3-overexpressing adenovirus or vehicle and then infused with AngII or saline using subcutaneously implanted mini-pumps for four weeks. Hearts were stained with hematoxylin-eosin, Masson's trichrome and immunohistochemical markers for histology. Primary fibroblasts were treated with the adenovirus and AngII and then examined using western blotting, EdU (5-ethynyl-2'-deoxyuridine) assays and immunofluorescence. Additionally, siRNA silencing was performed to study the role of DKK3 and the involved pathways. RESULTS: AngII-induced cardiac hypertrophy and interstitial and perivascular fibrosis were less severe in DKK3-overexpressing mice than in control mice. Moreover, the expression levels of fibrotic genes, such as collagen I and III, and the hypertrophic genes atrial natriuretic peptide (ANP) and beta-myosin heavy chain (ß-MHC) were decreased. DKK3 overexpression also exerted a protective effect by inhibiting ADAM17 phosphorylation, thus increasing ACE2 expression and subsequently promoting AngII degradation. Furthermore, this process was mediated by the inhibition of GSK-3ß and ß-catenin and decreased translocation of ß-catenin to the nucleus. On the other hand, the DKK3 knockdown by siRNA achieved opposite results. CONCLUSION: DKK3 overexpression substantially alleviated AngII infusion-induced cardiac hypertrophy and fibrosis by regulating ADAM17/ACE2 pathway activity and inhibiting the GSK-3ß/ß-catenin pathway.

Effective components screening and anti-myocardial infarction mechanism study of the Chinese medicine NSLF6 based on "system to system" mode.

BACKGROUND: Shuanglong formula (SLF), a Chinese medicine composed of panax ginseng and salvia miltiorrhiza exhibited significant effect in the treatment of myocardial infarction (MI) in clinical. Because of the complex nature and lack of stringent quality control, it's difficult to explain the action mechanism of SLF. METHOD: In this study, we present a "system to system" (S2S) mode. Based on this mode, SLF was simplified successively through bioactivity-guided screening to achieve an optimized minimal phytochemical composition (new formula NSLF6) while maintaining its curative effect for MI. RESULTS: Pharmacological test combining with the study of systems biology show that NSLF6 has activity for treatment MI through synergistic therapeutic efficacies between total ginsenosides and total salvianolic acids via promoting cardiac cell regeneration and myocardial angiogenesis, antagonistic myocardial cell oxidative damage. CONCLUSIONS: The present S2S mode may be an effective way for the discovery of new composite drugs from traditional medicines.

Rheological effects of blood in a nonplanar distal end-to-side anastomosis.

This study investigates rheological effects of blood on steady flows in a nonplanar distal end-to-side anastomosis. The shear-thinning behavior of blood is depicted by a Carreau-Yasuda model and a modified power-law model. To explore effects of nonplanarity in vessel geometry, a curved bypass graft is considered that connects to the host artery with a 90 deg out-of-plane curvature. Navier-Stokes equations are solved using a finite volume method. Velocity and wall shear stress (WSS) are compared between Newtonian and non-Newtonian fluids at different flow rates. At low flow rate, difference in axial velocity profiles between Newtonian and non-Newtonian fluids is significant and secondary flows are weaker for non-Newtonian fluids. At high flow rate, non-Newtonian fluids have bigger peak WSS and WSS gradient. The size of the flow recirculation zone near the toe is smaller for non-Newtonian fluids and the difference is significant at low flow rate. The nonplanar bypass graft introduces helical flow in the host vessel. Results from the study reveal that near the bed, heel, and toe of the anastomotic junction where intimal hyperplasia occurs preferentially, WSS gradients are all very big. At high flow rates, WSS gradients are elevated by the non-Newtonian effect of blood but they are reduced at low flow rates. At these locations, blood rheology not only affects the WSS and its gradient but also secondary flow patterns and the size of flow recirculation near the toe. This study reemphasizes that the rheological property of blood is a key factor in studying hemodynamic effects on vascular diseases.

Endothelial progenitor cells in angiogenesis.

Circulating blood contains a subtype of progenitor cells that have the capacity to differentiate into mature endothelial cells in vitro and in vivo. These cells have been termed endothelial progenitor cells (EPCs). The isolation of EPCs by adherence culture or magnetic microbeads has been described. EPCs are characterized by the expression of 3 markers, CD133, CD34, and the vascular endothelial growth factor receptor-2. After differentiation, EPCs express CD31, vascular endothelial cadherin, and von Willebrand factor. Evidence is accumulating that EPCs can facilitate endothelial repair and angiogenesis in vivo. We observed that EPCs can regenerate damaged endothelial cells in vascular grafts in apoE-deficient mice, and that abundant vascular progenitor cells are present in the adventitia of the vessel wall. It is not clear yet, however, whether these EPCs are essential for these angiogenic and atherogenic processes. Moreover, there are still many uncertainties about how cardiovascular risk factors alter EPC function. Thus, further studies on the mechanisms of EPC homing, releasing and attaching will be of help to explore areas of potential basic research and clinical application of EPCs.