Project description:Background: Excess fibrotic remodeling leads to cardiac dysfunction in ischemic heart disease and is driven by MAP kinase-dependent transforming growth factor-ß1 (TGF-ß1) activation by coagulation signaling of myeloid cells. How coagulation-inflammatory circuits can be specifically targeted to achieve beneficial macrophage reprogramming after myocardial infarction (MI) is incompletely understood. Methods: Mice with permanent ligation of the proximal left anterior descending artery (LAD) were used to model ischemic heart disease and analyzed by single cell RNA sequencing, protein expression changes, confocal microscopy, and longitudinal monitoring of recovery. We probed the role of the tissue factor (TF)-factor 7 (F7)-integrin ß1-protease activated receptor (PAR) 2 signaling complex by utilizing genetic mouse models and pharmacological intervention. Results: Cleavage-insensitive PAR2R38E and myeloid cell integrin ß1-deficient mice had improved cardiac function after MI compared to controls. Proximity ligation assays of monocytic cells in the infarcted myocardium demonstrated that colocalization of F7 with integrin ß1 was diminished in monocyte/macrophage F7-deficient mice. F7fl/fl CX3CR1Cre relative to littermate control mice showed reduced TGF-ß1 and MAP kinase activation, as well as cardiac dysfunction after MI, despite unaltered overall recruitment of myeloid cells into the infarct zone. Single cell mRNA sequencing of CD45+ cells 3 and 7 days after MI uncovered a trajectory from ischemic myocardium-recruited monocytes to inflammatory TF+/F7+/TREM1+ macrophages. As early as 7 days after MI, macrophage F7-deletion led to an expansion of Olfml3+ macrophages with a reparative phenotype and, conversely, to a reduction of TF+/F7+/TREM1+ macrophages, which were also attenuated in activation-resistant PAR2R38E mice. To demonstrate the therapeutic potential of inhibiting the TF-F7-PAR2 signaling complex,, we injected a specific monoclonal anti-TF antibody that lacks anticoagulant activity, but interferes with macrophage migration in vitro. Short-term treatment from day 1-5 after non-reperfused MI improved cardiac dysfunction, decreased excess fibrosis, attenuated vascular endothelial dysfunction, and increased survival 28 days after MI. Conclusions: Extravascular TF-F7-PAR2 complex signaling drives inflammatory macrophage polarization in ischemic heart disease. Targeting this signaling complex for specific therapeutic macrophage reprogramming following MI attenuates cardiac fibrosis and improves cardiovascular function.
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:The mechanistic target of rapamycin (mTOR) is a key regulator of pathological remodeling in the heart by activating ribosomal biogenesis and mRNA translation. Inhibition of mTOR in cardiomyocytes is protective, however, a detailed role of mTOR in translational regulation of specific mRNA networks in the diseased heart is largely unknown. A cardiomyocyte genome-wide sequencing approach was used to define mTOR-dependent post-transcriptional gene expression control at the level of mRNA translation. This approach identified the muscle specific protein Cullin-associated NEDD8-dissociated protein 2 (Cand2) as a translationally upregulated gene dependent on the activity of mTOR. Deletion of Cand2 protects the myocardium against pathological remodeling. Mechanistically, we found that Cand2 links mTOR- signaling to pathological cell growth by increasing Grk5 protein expression. Our data suggest that cell-type specific targeting of mTOR might have therapeutic value for adverse pathological cardiac remodeling.
Project description:Mononuclear phagocytes promote injury and repair following myocardial infarction but discriminating functions within mixed populations remains challenging. We utilized fate mapping and single cell RNA-sequencing to delineate fate specification trajectories of heterogeneous cardiac macrophage subpopulations. In steady state, TIMD4 expression tracked with a dominant resident cardiac macrophage subset that persisted via in situ self-renewal with minimal monocyte input. Following ischemic injury, monocytes displayed significant plasticity, ultimately adopting transcriptional states similar to resident macrophages, but also multiple unique states. Ischemic injury reduced resident macrophage abundance within infarct tissue, and despite transcriptional similarity, TIMD4 expression distinguished resident from recruited macrophages. Specific lineage-based depletion of resident cardiac macrophages resulted in depressed cardiac function and adverse remodeling primarily within the peri-infarct zone, the only region of the myocardium where resident macrophages expanded numerically following injury. Together, these data highlight a non-redundant, cardioprotective role of resident cardiac macrophages, and the diverse transcriptional fates recruited monocytes can adopt.
Project description:Functional oncogenic links between ErbB2 and ERRα in HER2+ breast cancer patients support a therapeutic benefit of co-targeted therapies. However, ErbB2 and ERRα also play key roles in heart physiology, and this approach could pose a potential liability to cardiovascular health. Herein, using integrated phosphoproteomic, transcriptomic and metabolic profiling, we uncovered molecular mechanisms associated with the adverse remodeling of cardiac functions in mice with combined attenuation of ErbB2 and ERRα activity. Genetic disruption of both effectors results in profound effects on cardiomyocyte architecture, inflammatory response and metabolism, the latter leading to a decrease in fatty acyl-carnitine species further increasing the reliance on glucose as a metabolic fuel, a hallmark of failing hearts. Furthermore, integrated omics signatures of ERRα loss-of-function and doxorubicin treatment exhibit common features of chemotherapeutic cardiotoxicity. These findings thus reveal potential cardiovascular risks in discrete combination therapies in the treatment of breast and other cancers.
Project description:After menopause, women lose the protective effect of female hormones and experience increased risk of adverse cardiac remodeling following myocardial infarction (MI). This may be due in part to the deleterious effects of genes encoded on the X chromosome. On average, 15% of genes located on the X chromosome escape inactivation in women, resulting in over expression. We hypothesize that with age T-cells escape X-chromosome inactivation (XCI), thus exacerbating the inflammatory response and resulting in adverse post-MI remodeling in women. We will use 2 aims to delineate a mechanism defining age effects on XCI and how this in turn influences T-cell mediated post-MI remodeling. Aim 1 will test the hypothesis that older females have an increased number of T-cells that escape XCI and exacerbate monocyte recruitment and activation post-MI. Aim 2 will test the hypothesis that female mice with T-cells that have escaped XCI will have adverse remodeling and decreased post-MI survival. Our understanding of sex differences especially the influence of sex chromosomes during post-MI remodeling and development of heart failure is lacking. The information obtained from the proposed experiments will have direct implications for medical management of women post-MI.