Project description:RATIONALE: Myocardial infarction (MI) triggers a dynamic microRNA response with the potential of yielding therapeutic targets. OBJECTIVE: We aimed to identify novel aberrantly expressed cardiac microRNAs post-MI with potential roles in adverse remodeling in a rat model, and to provide post-ischemic therapeutic inhibition of a candidate pathological microRNA in vivo. METHODS AND RESULTS: Following microRNA array profiling in rat hearts 2 and 14days post-MI, we identified a time-dependent up-regulation of miR-31 compared to sham-operated rats. A progressive increase of miR-31 (up to 91.4±11.3 fold) was detected in the infarcted myocardium by quantitative real-time PCR. Following target prediction analysis, reporter gene assays confirmed that miR-31 targets the 3´UTR of cardiac troponin-T (Tnnt2), E2F transcription factor 6 (E2f6), mineralocorticoid receptor (Nr3c2) and metalloproteinase inhibitor 4 (Timp4) mRNAs. In vitro, hypoxia and oxidative stress up-regulated miR-31 and suppressed target genes in cardiac cell cultures, whereas LNA-based oligonucleotide inhibition of miR-31 (miR-31i) reversed its repressive effect on target mRNAs. Therapeutic post-ischemic administration of miR-31i in rats silenced cardiac miR-31 and enhanced expression of target genes, while preserving cardiac structure and function at 2 and 4weeks post-MI. Left ventricular ejection fraction (EF) improved by 10% (from day 2 to 30 post-MI) in miR-31i-treated rats, whereas controls receiving scrambled LNA inhibitor or placebo incurred a 17% deterioration in EF. miR-31i decreased end-diastolic pressure and infarct size; attenuated interstitial fibrosis in the remote myocardium and enhanced cardiac output. CONCLUSION: miR-31 induction after MI is deleterious to cardiac function while its therapeutic inhibition in vivo ameliorates cardiac dysfunction and prevents the development of post-ischemic adverse remodeling.
Project description:Lysosomes are at the epicenter of cellular processes critical for inflammasome activation in macrophages, including autophagy and lipid metabolism. Inflammasome activation and IL1-beta secretion are implicated in atherogenesis, ischemic cardiac injury and resultant heart failure; however, little is known about the role of macrophage lysosome function in regulating these processes. We hypothesized that macrophages exhibit lysosome dysfunction in heart failure due to ischemic injury, and that augmentation of macrophage lysosomal biogenesis via macrophage-specific overexpression of transcription factor EB (mf-TFEB) would attenuate ischemic remodeling by modulating macrophage inflammatory responses. In both mice subject to ischemia-reperfusion injury, and human heart tissue from patients with ischemic cardiomyopathy, we find evidence of lysosome insufficiency and autophagic impairment, respectively. Mf-TFEB overexpression significantly attenuated post-IR adverse left ventricular remodeling at 4 weeks without affecting scar size. Mf-TFEB overexpression reduced the relative amounts of pro-inflammatory macrophage populations in the myocardium. RNA sequencing of flow-sorted cardiac macrophages post-IR confirmed that TFEB stimulated a lysosomal transcriptional program in macrophages, and upregulated key targets involved in lysosomal lipid metabolism, which we show are critical for inflammasome suppression. Both TFEB-dependent inflammasome suppression and effects on post-IR remodeling were independent of autophagy. Our findings suggest that TFEB reprograms macrophage lysosomal lipid metabolism to attenuate inflammasome activity and protect against post-ischemic cardiac remodeling and simultaneously shift our understanding of how autophagy and lipid metabolism impact acute inflammation.
Project description:Cardiovascular disease is the main cause of death worldwide, making it crucial to search for new therapies to mitigate major adverse cardiac events (MACEs) after a cardiac ischemic episode. Drugs in the class of the glucagon-like peptide-1 receptor agonists (GLP1Ra) have demonstrated benefits for heart function and reduced the incidence of MACE in patients with diabetes. Previously, we demonstrated that a short-acting GLP1Ra known as DMB (2-quinoxalinamine, 6,7-dichloro-N-[1,1-dimethylethyl]-3-[methylsulfonyl]-,6,7-dichloro-2-methylsulfonyl-3-N-tert-butylaminoquinoxaline or compound 2, Sigma) also mitigates adverse postinfarction left ventricular remodeling and cardiac dysfunction in lean mice through activation of parkin-mediated mitophagy following infarction. Here, we combined proteomics with in silico analysis to characterize the range of effects of DMB in vivo throughout the course of early postinfarction remodeling. We demonstrate that the mitochondrion is a key target of DMB and mitochondrial respiration, oxidative phosphorylation and metabolic processes such as glycolysis and fatty acid beta-oxidation are the main biological processes being regulated by this compound in the heart. Moreover, the overexpression of proteins with hub properties identified by protein–protein interaction networks, such as Atp2a2, may also be important to the mechanism of action of DMB.
Project description:Stroke is frequently associated with cardiac troponin increase and cardiac complications. 24h and 72h after experimental ischemic stroke of the brain, we harvested the heart to investigate pathways and target genes, involved in cardiac dysfunction after acute ischemic stroke
Project description:Cardiac resident MerTK+ macrophages exert multiple protective roles post-ischemic injury, however, the mechanisms regulating their fate are not fully understood. Here we show that GAS6-inducible transcription factor ATF3 prevents apoptosis of MerTK+ macrophages after ischemia-reperfusion (IR) injury, by repressing the transcription of multiple genes involved in type I interferon expression (Ifih1 and Infb1) and apoptosis (Apaf1). Mice lacking ATF3 in cardiac macrophages or myeloid cells showed excessive loss of MerTK+ cardiac macrophages, poor angiogenesis, and worse heart dysfunction post-IR, which were rescued by the transfer of MerTK+ cardiac macrophages. GAS6 administration improved cardiac repair in an ATF3-dependent manner. Finally, we showed a negative association of GAS6 and ATF3 expression with the risk of major adverse cardiac events in patients with ischemic heart disease. These results indicate that the GAS6-ATF3 axis has a protective role against IR injury by regulating MerTK+ cardiac macrophage survival/proliferation.
Project description:Right ventricular heart failure (RVF) associated with pulmonary hypertension (PH) is characterized by a distinct gene expression pattern when compared with functional compensatory hypertrophy. Carvedilol treatment after RVF has been established reduces right ventricle (RV) hypertrophy and improves the RV function. In addition, carvedilol treatment has been shown to alter the gene expression of select genes. We sought to identify, on a genome-wide basis, the effect of carvedilol on gene expression. RVF was induced in male Sprague-Dawley rats by the combination of VEGF-receptor blockade and chronic hypoxia; thereafter, one group was treated with carvedilol. RNA was isolated from the RV and subjected to microarray analysis. A prediction analysis of the carvedilol-treated RVs showed that carvedilol treated RVs most resembled in their expression pattern the RVF pattern. However, an analysis beyond the boundaries of the prediction set revealed a small set of genes associated with carvedilol reversal of RVF. Pathway analysis of this set of genes revealed expression changes of genes involved in cardiac hypertrophy, mitochondrial dysfunction, protein ubiquitination, and sphingolipid metabolism. Genes encoding proteins in the cardiac hypertrophy and protein ubiquitination pathways were downregulated in the RV by carvedilol, while genes encoding proteins in the mitochondrial dysfunction and sphingolipid metabolism pathways were upregulated by carvedilol.
Project description:Pathologically elevated mechanical load promotes the adverse remodeling of left ventricle (LV) post myocardial infarction, which results in the progression from ischemic cardiomyopathy to heart failure. Cardiac patches could attenuate adverse LV remodeling by providing mechanical support to infarcted and border zone myocardium. However, the mechanism of the translation from mechanical effects to favorable therapeutic outcome is still not clear. This study aims to strengthen the foundation of the theory of cardiac patch treatment. By transcriptome analysis, we found that the myocardial transcription levels of mechanosensitive ion channel proteins Piezo1 and Piezo2 significantly increased in patients with ischemic cardiomyopathy. In vitro tensile tests with local tissue information and finite element modeling revealed a significant decrease in local strain and mechanical load in rat infarcts and sheep LV. Cardiac function and geometry were preserved compared to non-treated control. Further, in LV myocardium of the patch-treated group, MI induced expression levels of Piezo1/2 were significantly reverted to the similar levels of the control group, indicating that Piezo1/2 are key contributors as mechanosensor which initiated the signaling cascade and translated the beneficial mechanical support to therapeutic effects. These findings demonstrated the potential of cardiac patches in treating ICM patients with remodeling risks, and could provide guidance for improvement in next generation of patch devices.