Aging is a major risk factor for impaired cardiovascular health. Because the aging myocardium is characterized by microcirculatory dysfunction, and because nerves align with vessels, we assessed the impact of aging on the cardiac neurovascular interface. We report that aging reduces nerve density in the ventricle and dysregulates vascular-derived neuroregulatory genes. Aging down-regulates microRNA 145 (miR-145) and derepresses the neurorepulsive factor semaphorin-3A. miR-145 deletion, which increased Sema3a expression or endothelial Sema3a overexpression, reduced axon density, mimicking the aged-heart phenotype. Removal of senescent cells, which accumulated with chronological age in parallel to the decline in nerve density, rescued age-induced denervation, reversed Sema3a expression, preserved heart rate patterns, and reduced electrical instability. These data suggest that senescence-mediated regulation of nerve density contributes to age-associated cardiac dysfunction.

BACKGROUND: Morbidity and mortality of heart failure with preserved ejection fraction (HFpEF) is increased in metabolic disorders. However, options for preventing and treating these prevalent outcomes are limited. Intramyocardial lipotoxicity contributes to cardiac dysfunction. Here, we investigate the mechanisms underlying EDEM2 (endoplasmic reticulum degradation–enhancing alpha-mannosidase–like protein 2) regulation of cardiac lipid homeostasis and assess strategies that inhibit the incidence and progression of HFpEF. METHODS: Metabolic stress was induced in C57BL/6 male mice using a high-fat diet and N ω-nitro-L-arginine methyl ester. The recombinant adeno-associated virus 9 delivery system was used for loss- and gain-of-function studies. Palmitic acid and oleic acid stimulation of rat cardiomyocytes and human induced pluripotent stem cell–derived cardiomyocytes imitated a condition of high lipids in vitro. Molecular mechanisms were investigated via RNA sequencing, mass spectrometry proteomics, lipidomic analyses, transmission electron microscopy, histology, and luciferase reporter assays. RESULTS: In the human heart, we first detected lipid overload accompanied by a reduction of XBP1 (X-box binding protein 1) under metabolic stress. Thereafter, a decrease in EDEM2 was confirmed in human and mouse HFpEF hearts. Given that XBP1s (spliced X-box binding protein 1) is a transcription factor, EDEM2 was identified as its new target in cardiomyocytes. EDEM2 knockdown mice manifested lipid droplet accumulation and higher levels of triglycerides and diglycerides in the myocardium, aggravating oxidative stress, hypertrophy, and the onset and progression of HFpEF under metabolic stress. XBP1s ablation mice displayed a similar myocardial lipid disturbance and cardiac phenotypes, which were reversed by EDEM2 overexpression. Mechanistically, the findings obtained from rat cardiomyocytes and human induced pluripotent stem cell–derived cardiomyocytes demonstrated that, in the presence of EDEM2, SEC23A mediated intracellular translocation of ATGL (adipose triglyceride lipase) under fatty acid stimulation, inhibiting ATGL degradation and excessive intracellular lipid droplets. Furthermore, the functional studies supported that EDEM2 prevention of lipid overload occurred in an ATGL-dependent manner. Therapeutically, cardiac XBP1s or EDEM2 restoration mitigated lipid deposition and preserved lipid profiles in the myocardium, thus preventing the development of HFpEF. CONCLUSIONS: We demonstrate a cardioprotective mechanism regulating myocardial lipid homeostasis. The findings provide a promising therapeutic target to prevent and treat HFpEF, a condition with limited treatment options.

BACKGROUND: Advanced age is unequivocally linked to the development of cardiovascular disease; however, the mechanisms resulting in reduced endothelial cell regeneration remain poorly understood. Here, we investigated novel mechanisms involved in endothelial cell senescence that impact endothelial cell transcription and vascular repair after injury. METHODS: Native endothelial cells were isolated from young (20±3.4 years) and aged (80±2.3 years) individuals and subjected to molecular analyses to assess global transcriptional and metabolic changes. In vitro studies were conducted using primary human and murine endothelial cells. A murine aortic re-endothelialization model was used to examine endothelial cell regenerative capacity in vivo. RESULTS: RNA sequencing of native endothelial cells revealed that aging resulted in p53-mediated reprogramming to express senescence-associated genes and suppress glycolysis. Reduced glucose uptake and ATP contributed to attenuated assembly of the telomerase complex, which was required for endothelial cell proliferation. Enhanced p53 activity in aging was linked to its acetylation on K120 due to enhanced activity of the acetyltransferase MOZ (monocytic leukemic zinc finger). Mechanistically, p53 acetylation and translocation were, at least partially, attributed to the loss of the vasoprotective enzyme, CSE (cystathionine γ-lyase). CSE physically anchored p53 in the cytosol to prevent its nuclear translocation and CSE absence inhibited AKT (Protein kinase B)-mediated MOZ phosphorylation, which in turn increased MOZ activity and subsequently p53 acetylation. In mice, the endothelial cell–specific deletion of CSE activated p53, induced premature endothelial senescence, and arrested vascular repair after injury. In contrast, the adeno-associated virus 9–mediated re-expression of an active CSE mutant retained p53 in the cytosol, maintained endothelial glucose metabolism and proliferation, and prevented endothelial cell senescence. Adenoviral overexpression of CSE in native endothelial cells from aged individuals maintained low p53 activity and reactivated telomerase to revert endothelial cell senescence. CONCLUSIONS: Aging-associated impairment of vascular repair is partly determined by the vasoprotective enzyme CSE.

BACKGROUND: Endothelial cells (ECs) play pivotal roles in maintaining cardiac blood supply and regulating inflammation by acting as gatekeepers for immune cell activity. This study unveils a novel immunomodulatory function of cardiac ECs following myocardial infarction. METHODS: We used single-cell RNA sequencing and spatial transcriptomics to identify EC states after acute myocardial infarction in mice. Subsequently, we mimicked the cytokine environment that was predicted to induce EC activation in cell culture studies and confirmed the results in an endothelial-specific deletion mouse model. RESULTS: Single-cell RNA sequencing analysis identified a transient myeloid CD45 ⁺ CD11b ⁺ Cdh5 ⁺ immunomodulatory EC phenotype (IMEC) emerging between days 1 and 3 after myocardial infarction. IMECs derived from Cdh5 ⁺ tissue resident cells as shown by bone marrow transplantation and lineage tracing experiment. Ligand-receptor interaction predictions indicated a cytokine-mediated activation of IMECs, which we validated through in vitro experiments in cultured ECs. Notably, while cytokine treatment with IL-1β and TGF-β (transforming growth factor β) induced mesenchymal gene expression, the addition of IFN-γ (interferon γ) facilitated the transition into the immunomodulatory phenotype. IMECs exhibited an upregulation of MHC-II (major histocompatibility complex class II) genes, along with the expression of RUNX1 (runt-related transcription factor-1) and proinflammatory cytokines, such as IL-6 and IL-12. IMECs induced T-cell activation through paracrine signaling and were colocalized with T cells in vivo. Inhibition of endothelial-specific IFN-γ-signaling in mice by IFN-γ receptor 1 deletion improved the recovery after myocardial infarction. CONCLUSIONS: These findings provide insight into the role of ECs regulating adaptive immune responses following myocardial infarction, offering potential insights into therapeutic interventions for postinfarction immunomodulation.

(1) Background: Diabetic cardiomyopathy is a major health problem worldwide. CTRP9, a secreted glycoprotein, is mainly expressed in cardiac endothelial cells and becomes downregulated in mouse models of diabetes mellitus; (2) Methods: In this study, we investigated the impact of CTRP9 on early stages of diabetic cardiomyopathy induced by 12 weeks of high-fat diet; (3) Results: While the lack of CTRP9 in knock-out mice aggravated insulin resistance and triggered diastolic left ventricular dysfunction, AAV9-mediated cardiac CTRP9 overexpression ameliorated cardiomyopathy under these conditions. At this early disease state upon high-fat diet, no fibrosis, no oxidative damage and no lipid deposition were identified in the myocardium of any of the experimental groups. Mechanistically, we found that CTRP9 is required for insulin-dependent signaling, cardiac glucose uptake in vivo and oxidative energy production in cardiomyocytes. Extensive RNA sequencing from myocardial tissue of CTRP9-overexpressing and knock-out as well as respective control mice revealed that CTRP9 acts as an anti-inflammatory mediator in the myocardium. Hence, CTRP9 knock-out exerted more, while CTRP9-overexpressing mice showed less leukocytes accumulation in the heart during high-fat diet; (4) Conclusions: In summary, endothelial-derived CTRP9 plays a prominent paracrine role to protect against diabetic cardiomyopathy and might constitute a therapeutic target.

Background: Prolonged activation of angiotensin II is the main mediator that contributes to the development of heart diseases, so converting angiotensin II into angiotensin 1‐7 has emerged as a new strategy to attenuate detrimental effects of angiotensin II. Prolylcarboxypeptidase is a lysosomal pro‐X carboxypeptidase that is able to cleave angiotensin II at a preferential acidic pH optimum. However, insufficient attention has been given to the cardioprotective functions of prolylcarboxylpeptidase. Methods and Results: We established a CRISPR/CRISPR‐associated protein 9–mediated global prolylcarboxylpeptidase‐knockout and adeno‐associated virus serotype 9–mediated cardiac prolylcarboxylpeptidase overexpression mouse models, which were challenged with the angiotensin II infusion (2 mg/kg per day) for 4 weeks, aiming to investigate the cardioprotective effect of prolylcarboxylpeptidase against hypertensive cardiac hypertrophy. Prolylcarboxylpeptidase expression was upregulated after 2 weeks of angiotensin II infusion and then became downregulated afterward in wild‐type mouse myocardium, suggesting its compensatory function against angiotensin II stress. Moreover, angiotensin II–treated prolylcarboxylpeptidase‐knockout mice showed aggravated cardiac remodeling and dampened cardiac contractility independent of hypertension. We also found that prolylcarboxylpeptidase localizes in cardiomyocyte lysosomes, and loss of prolylcarboxylpeptidase led to excessive angiotensin II levels in myocardial tissue. Further screening demonstrated that hypertrophic prolylcarboxylpeptidase‐knockout hearts showed upregulated extracellular signal‐regulated kinases 1/2 and downregulated protein kinase B activities. Importantly, adeno‐associated virus serotype 9–mediated restoration of prolylcarboxylpeptidase expression in prolylcarboxylpeptidase‐knockout hearts alleviated angiotensin II–induced hypertrophy, fibrosis, and cell death. Interestingly, the combination of adeno‐associated virus serotype 9–mediated prolylcarboxylpeptidase overexpression and an antihypertensive drug, losartan, likely conferred more effective protection than a single treatment protocol to mitigate angiotensin II–induced cardiac dysfunction. Conclusions: Our data demonstrate that prolylcarboxylpeptidase protects the heart from angiotensin II–induced hypertrophic remodeling by controlling myocardial angiotensin II levels.