Circulation research最新文献

Background: Cardiac fibrosis can be triggered by several pathologies, including ischemic heart disease and aortic stenosis. Cardiac fibrosis is brought about by uncontrolled ECM (extracellular matrix) deposition by myofibroblasts. IL (interleukin)-11 (Il11) has been demonstrated as a trigger of multiorgan fibrosis. However, the molecular mechanisms underpinning IL-11-induced fibrosis require further characterization. Recent studies indicate that microRNA dysregulation contributes to the pathogenesis of cardiac fibrosis and can be targeted therapeutically. This study explored the hypothesis that microRNAs act as downstream effectors of IL-11-induced cardiac fibrosis. Moreover, we investigated the translational potential of IL-11-regulated microRNAs as circulating biomarkers of cardiac fibrosis in patients with aortic stenosis.

Methods: A bioinformatic microRNA target prediction analysis was used to identify candidate microRNAs regulated by IL-11. Experimental validation was performed in cardiac fibroblasts from postinfarction failing and healthy rat hearts, after IL-11 stimulation. Functional studies assessed the effects of microRNA modulation on fibrotic gene expression in cardiac fibroblasts using microRNA inhibitor-based and mimic-based transfection. Bioinformatic analysis and luciferase assay identified candidate microRNA targets downstream of IL-11. Findings were further evaluated in transverse aortic constriction and cardiomyocyte-specific Il11-overexpression (Tg-Il11 [transgenic mouse model with cardiomyocyte-specific Il11 overexpression]) mouse models and in left ventricular tissue, peripheral plasma, and plasma extracellular vesicles from patients with aortic stenosis.

Results: MicroRNA-27b-5p and microRNA-497-5p were identified as novel downstream effectors of IL-11 signaling. IL-11 increased the expression of both microRNAs in cardiac fibroblasts; transfection with either microRNA inhibitor reduced, whereas microRNA mimics increased, profibrotic mRNA levels. Furthermore, microRNA-27b-5p and microRNA-497-5p converged on HIF (hypoxia-inducible factor)-1 signaling by targeting its regulator egl-9 homolog (EGLN [Egl-9 family hypoxia-inducible factor]). Increased microRNA levels were observed alongside reduced expression of Egln1 and Egln2 in 2 mouse models. In patients with aortic stenosis, myocardial and circulating levels of these microRNAs correlated with the severity of left ventricular fibrosis, indicating these microRNAs' potential as new circulating biomarkers of cardiac fibrosis.

Conclusions: In this study, we have newly identified the potential value of microRNA-27b-5p and microRNA-497-5p as actionable biomarkers of the profibrotic response to IL-11 in the heart. Future studies should validate the translational potential of the microRNAs as new clinical biomarkers and therapeutic targets.

Background: Nonmyocytes may contribute to regional adaptive changes during persistent atrial fibrillation (PsAF), favoring its perpetuation. We aimed to investigate the differential features of fibroblast and macrophage populations within individual-specific atrial regions associated with PsAF maintenance.

Methods: The study was conducted in 2 pig models of PsAF with and without infarct-related substrate (N=27 and N=27, respectively) and further validated in humans with PsAF (N=20). Sham-operated pigs (N=9), healthy animals (N=4), and patients in sinus rhythm (N=7) were used as comparative controls. In pigs, in vivo high-density instantaneous frequency modulation maps were used to identify atrial regions associated with PsAF maintenance (drivers). Regional cellular composition and phenotypic states of fibroblast and myeloid lineages were determined using flow cytometry, single-cell RNA sequencing, immunohistochemistry, and proteomic analyses. The functional relevance of driver regions was further studied in patients with symptomatic PsAF undergoing ablation. Flow cytometry and single-cell RNA sequencing analyses were performed in tissue samples of the left atrial appendage in a complementary cohort of patients with PsAF undergoing thoracoscopic-guided ablation.

Results: PsAF terminated acutely in 12 of 14 pigs undergoing mapping and ablation of driver regions. In humans, driver ablation was associated with 90% AF-freedom (on/off antiarrhythmic drugs) after 2 years of follow-up. Samples from nonablated pigs revealed a phenotypic shift towards ACTA2 (actin alpha 2)-fibroblasts and PTX3 (pentraxin 3)-fibroblasts during PsAF. Although ACTA2-fibroblasts were highly preserved in human samples, paired comparisons in pig samples showed that PTX3-fibroblasts were enriched only in driver regions. PsAF also showed changes in myeloid cells towards inflammatory profiles. However, regional analysis revealed that, in both humans and pigs with PsAF, driver regions were enriched in cardiac resident macrophages with transcriptomic and proteomic profiles favoring cardiomyocyte homeostasis and cell survival.

Conclusions: PsAF shows differential regional changes in fibroblast and myeloid populations with distinctive gene signatures in areas that drive the overall arrhythmia.

Background: The nervous, gastrointestinal, renal, and cardiovascular systems orchestrate ion-fluid homeostasis and impose reciprocal adaptations to hypertensive challenges. Mechanistic insight into the interorgan crosstalk is fundamental for tackling pathogenesis of hypertensive heart disease.

Methods: We integrated gut microbiome profiling and targeted metabolomics in a zebrafish model of ion dyshomeostasis-induced diastolic dysfunction to identify microbial metabolites linked to hypertensive cardiac remodeling. To dissect the gut-brain-heart axis, we depleted microbiota, supplemented specific microbial metabolites, and chemogenetically ablated hypothalamic neurons. Neuronal activity was monitored using in vivo calcium imaging and immunohistochemistry, and cardiovascular function was assessed by live imaging. Patient serum metabolic profiles were analyzed to evaluate relevance to human hypertension.

Results: Zebrafish larvae exposed to ion dyshomeostasis exhibited gut dysbiosis, marked by reduced microbial richness and diversity, particularly among indole- and indole-3-producing taxa. Functionally, commensal microbiota protected against cardiovascular structural and functional remodeling during hypertensive challenge, whereas antibiotic-induced perturbation worsened hemodynamic parameters of arterial hypertension and impaired ventricular relaxation. Gut metabolomics identified a lower abundance of indole-3 acetic acid as a key signature of the hypertensive response, a pattern conserved in serum metabolome from patients with hypertension. Indole-3 acetic acid supplementation, acting via the aryl hydrocarbon receptor, mitigated cardiac concentric hypertrophy and diastolic dysfunction. These effects involved hypothalamic hypocretin neurons, with indole-3 acetic acid suppressing their overactivation and the associated sympathetic overdrive in cardiac-projecting paravertebral ganglia during the hypertensive challenge. Indole-3 acetic acid also prevented renin-angiotensin-aldosterone system upregulation, indicating that it operates upstream of both autonomic and hormonal pathways.

Conclusions: Our findings uncover a gut-brain-heart crosstalk where hypertensive gut dysbiosis signals to the central nervous system to drive diastolic remodeling. Modulation of indole-3 acetic acid signaling and hypocretin neuron activity represents a promising strategy to counter the multisystemic pathogenesis of hypertensive heart disease.

Background: Myocardial infarction (MI) results in 3 distinct regions within the left ventricle: the infarct zone, the border zone (BZ), and the remote zone. A major focus of MI research is investigating the intrinsic mechanisms in the BZ to alleviate myocardial injury. USP10 (ubiquitin-specific peptidase 10) expression is reduced in BZ cardiomyocytes, indicating potential for targeted therapeutic intervention.

Methods: Isolated BZ cardiomyocytes and hypoxia-treated neonatal rat cardiomyocytes were used to investigate the expression of USP10 in MI. Cultured neonatal rat cardiomyocytes and genetically engineered mice were used to assess the importance of USP10 in the context of MI. Immunoprecipitation mass spectrometry and ubiquitination assays were used to explore the mechanisms by which USP10 suppresses the cGAS (cyclic GMP-AMP synthase) stimulator of interferon genes (STING) pathway.

Results: Our study reveals that USP10 is critical in protecting against cardiac injury following MI. Specifically, USP10 mitigates MI-induced mitochondrial dysfunction and prevents the release of mitochondrial DNA into the cytosol, thereby inhibiting the activation of the cGAS-STING signaling pathway. Additionally, USP10 deubiquitinates the K48-linked ubiquitination of MTX2 (metaxin 2), thus enhancing MTX2 protein stability. We identified K93 as a critical ubiquitination site on MTX2 through mutagenesis analysis. Importantly, our findings demonstrate that the MTX2-K93R mutation rectifies USP10 loss-induced exacerbation of MI.

Conclusions: This study identifies USP10 as a novel regulator of the cGAS-STING signaling pathway in MI. Moreover, our findings demonstrate that a decrease in USP10 in the BZ cardiomyocytes can be therapeutically targeted to mitigate cardiac injury in MI.

Background: Disorders in pulmonary vascular integrity are a prominent feature in many lung diseases. Paracrine signaling is highly enriched in the lung and plays a crucial role in regulating vascular homeostasis. However, the specific local cell-cell crosstalk signals that maintain pulmonary microvascular stability in adult animals and humans remain largely unexplored.

Methods: In this study, we used single-cell RNA-sequencing-based computational pipelines to systematically profile ligand-receptor interactions within the lung microvascular niche and identified VEGF-D (vascular endothelial growth factor-D) as a key local factor with previously unrecognized barrier-protective properties in models of acute lung injury.

Results: Our single-cell RNA-sequencing data revealed that, under physiological conditions, soluble ligand-receptor interactions between mesenchymal cells, in particular alveolar fibroblasts, and microvascular endothelial cells are predominantly associated with pathways involved in maintaining vascular integrity as compared with all other cells. On treatment with top identified ligands, we found that VEGF-D significantly enhanced endothelial barrier function and conferred protection against inflammatory challenges induced by TNF-α (tumor necrosis factor-α), IL (interleukin)-1β, and thrombin. This barrier-protective effect of VEGF-D was significantly attenuated by inhibition of VEGFR2 (vascular endothelial growth factor receptor 2), either through siRNA knockdown or pharmacological blockade using specific VEGFR2 inhibitors. Intravenous administration of recombinant VEGF-D in lipopolysaccharide-induced acute lung injury models significantly reduced vascular permeability (7339±2510 a.u. [lipopolysaccharides] versus 5350±1821 a.u. [lipopolysaccharides+VEGF-D]; P<0.05), immune cell infiltration (0.791±0.199×10⁶ whole blood cells/mL [lipopolysaccharides] versus 0.540±0.190×10⁶ whole blood cells/mL [lipopolysaccharide+VEGF-D]; P<0.01), and the expression of proinflammatory markers TNF-α, IL-6, and keratinocyte chemoattractant in the lung tissue. This effect was abolished in VEGFR2^iECKO (VEGFR2 inducible endothelial cells knockout) mice, confirming that VEGF-D mediates its effects via VEGFR2-dependent signaling.

Conclusions: This study demonstrates an unexpected protective role for VEGF-D in promoting lung endothelial barrier integrity and suggests that paracrine signaling from the alveolar fibroblast niche contributes critically to lung capillary homeostasis.