JACC: Basic to Translational Science

Glutathione peroxidase 4 (GPX4) is an antioxidant enzyme important for the reduction of toxic lipid peroxide products. Previous studies revealed the importance of mouse Gpx4 in protecting cardiomyocytes from ferroptosis and, subsequently, the development of cardiovascular disease. In this paper, we investigate the transcriptional consequences of cardiac-specific deletion of Gpx4 in mice and compare this response with that observed in human cardiomyopathy. The findings in this study highlight the importance of GPX4 in maintaining both structural and functional stability of the heart and identify key pathway changes resulting from excessive ferroptosis in cardiac tissue. By overlapping common transcriptional programs perturbed in this animal model and human cardiomyopathy, our findings identify putative mechanisms through which ferroptosis contributes to the development and progression of heart disease. These studies may help guide future cardiovascular therapeutics targeting ferroptosis-dependent pathways.

BackgroundPrimary mitral regurgitation resulting from mitral valve prolapse can lead to life-threatening complications, including arrhythmias, heart failure, and sudden cardiac death. Mitral valve prolapse is classically associated with myxomatous mitral valve degeneration, characterized by leaflet thickening, extracellular matrix disorganization, and progressive structural remodeling. Valvular interstitial cells, the predominant stromal population within the valve, maintain extracellular matrix homeostasis; however, their molecular heterogeneity, and state-specific contributions to disease pathogenesis remain incompletely defined. MethodsUsing a fibrillin-1 deficient mouse model and human tissue specimens we integrated single-cell RNA sequencing with spatial transcriptomic profiling to construct a comprehensive atlas of cellular composition and extracellular matrix organization across normal mitral valves, sporadic mitral valve prolapse, and Marfan syndrome-associated mitral valve prolapse. ResultsAnalyses revealed spatially organized cellular niches and substantial heterogeneity within the valvular interstitial cell population. Across murine and human datasets, we identified a conserved activated valvular interstitial cell population enriched for profibrotic extracellular matrix remodeling programs and preferentially localized to mechanically vulnerable leaflet tip regions. This population exhibited coordinated upregulation of collagen- and matrix-associated genes, metabolic signatures consistent with enhanced mitochondrial activity, and transcriptional features suggesting fibro-inflammatory signaling. ConclusionsWe identified a transcriptionally and spatially distinct activated valvular interstitial cell state conserved across species and disease etiologies that is strongly implicated in fibrotic remodeling during myxomatous mitral valve degeneration and provides a candidate therapeutic target.

Background Current management of pediatric dilated cardiomyopathy (DCM) in children relies on guideline-directed medical therapy (GDMT) extrapolated from adult heart failure. However, due to small sample size, randomized trials of GDMT agents in children have failed to demonstrate efficacy and mortality benefits seen in adults, suggesting fundamental differences in disease mechanisms. We hypothesized that distinct age-dependent transcriptional programs underlie this therapeutic discordance. Methods We performed comparative transcriptomic profiling using bulk RNA sequencing on explanted left ventricular tissue from pediatric (n=29) and adult (n=35) DCM patients (adult DCM from previously published data) compared with age-matched non-failing controls (n=22 pediatric, 14 adult). We analyzed differential gene expressions, pathway enrichment across disease etiologies, and the regulation of a conserved 430-gene {beta}1-adrenergic receptor gene signaling network ({beta}1-GSN) known to modulate remodeling in adult heart failure. Results Transcriptional signatures were profoundly distinct, with only 7.4% of differentially expressed genes shared between adult and pediatric cohorts. Pediatric DCM was characterized by transcriptional reprogramming and the activation of developmental pathways, including WNT/{beta}-catenin and Notch signaling. Conversely, adult DCM hearts were enriched for pathways associated with metabolic dysfunction, mitochondrial deficits, and inflammation. Crucially, while the {beta}1-GSN was desensitized and extensively remodeled in adults, the pathway remained activated in children, with only 4 of 430 network genes showing antithetical regulation. Conclusion The lack of pathological {beta}-adrenergic remodeling in children could provide a molecular explanation for the lack of clear efficacy of {beta}-blockers in this population. Collectively, these results suggest pediatric DCM represents a biologically distinct disease entity rather than an earlier manifestation of adult heart failure, and future therapeutic strategies must move beyond adult extrapolation to target pediatric-specific pathways.

BACKGROUNDInactivation of ANGPTL3 (angiopoietin-like protein 3, A3) is a proven therapeutic strategy for lowering plasma lipid levels independently of the LDL receptor (LDLR), yet the optimal approach to inactivate A3 remains unclear. A3 is proteolytically cleaved and circulates as full-length (A3-FL), N-terminal (A3-Nter) and C-terminal (A3-Cter) fragments. The specific contribution of each form of A3, and of its paralog, ANGPTL8 (A8), in modulating circulating levels of ApoB-Containing Lipoproteins (ABCLs) remain poorly defined. Clarifying these relationships will inform next-generation A3-directed therapies. METHODSWe performed liver perfusion studies to directly compare the number and composition of VLDL particles secreted from mice with and without A3. To amplify effects on cholesterol metabolism, we generated Ldlr-/- mice expressing wildtype A3 (A3-WT), A3-FL or A3-Nter, with or without co-expression of A8, and analyzed plasma lipids, circulating A3 and A8 complexes, and intravascular lipase activities. Complementary in vitro assays and structural modeling were used to assess relative endothelial lipase (EL) inhibition by A3 alone or in complex with A8. RESULTSLiver perfusion studies revealed that A3 inactivation does not alter the rates of hepatic secretion of VLDL in wildtype or Ldlr-/- mice. Inactivation of A8 alone lowered plasma LDL-cholesterol (C) levels by [~]20%, an effect dependent upon the expression of both EL and A3. Maximal inhibition of lipoprotein lipase (LPL) required co-expression of A8 plus both A3-FL and A3-Nter, indicating that A3 cleavage, in addition to A8 expression, is essential for maximal LPL inhibition. In contrast, A8 expression, but not A3 cleavage, was required for optimal EL inhibition. CONCLUSIONSA8 acts in concert with A3 to differentially modulate LPL- and EL-mediated lipolysis, which antagonizes hepatic clearance of newly-secreted atherogenic ABCLs. This mechanistic framework refines our understanding of A3-targeted lipid lowering and highlights the therapeutic potential of dual A3- plus A8-directed strategies to treat dyslipidemia and prevent atherosclerotic cardiovascular disease. Clinical perspectiveO_ST_ABSWhat is new?C_ST_ABSO_LIInactivation of A3 lowers circulating ABCL levels without altering hepatic secretion rates of VLDL-ApoB or -TG. C_LIO_LIProteolytic cleavage of A3 is required for maximal inhibition of LPL. C_LIO_LIInactivation of A8 lowers LDL-C levels through an A3- and EL-dependent, but LDLR-independent, mechanism. C_LI What are the clinical implications?O_LICombining A8 inhibition with A3-inactivating therapies offers a strategy to achieve greater reduction in LDL-C levels and atherosclerotic cardiovascular risk. C_LI

BACKGROUNDMono-ADP ribosylation is a post-translational modification that regulates various cellular physiological processes, including cell cycle progression, genomic stability, transcription, and cellular protein turnover. PARP16 is an endoplasmic reticulum (ER)-localized mono-ADP-ribosyltransferase that has been shown to regulate the unfolded protein response and maintain ER homeostasis under stress conditions. Despite its established role in ER stress signaling, the functional significance of PARP16 in cardiac pathophysiology, particularly in cardiac hypertrophy and heart failure, remains poorly understood. In this study, we aim to investigate the role of PARP16 in cardiac hypertrophy and heart failure using in vitro and mouse model systems. METHODSWe analysed PARP16 expression in human heart failure samples as well as in heart failure-based mouse models. We evaluated gene expression by RT-PCR, immunoblotting, and confocal microscopy to understand the role of PARP16 in heart failure under phenylephrine- or isoproterenol-treated conditions. We also investigated the role of PARP16 in regulating cardiac function in genetically engineered mouse models, including whole-body PARP16 knockout, cardiac-specific PARP16 knockout, inducible cardiac-specific PARP16 knockout, and cardiac-specific PARP16 Transgenic mice. We performed echocardiography to assess cardiac function. We also used an in vitro primary cardiomyocyte system to knock down and overexpress PARP16. We performed RNA sequencing and mass spectrometry, followed by molecular docking, molecular dynamics simulation, immunoprecipitation, and luciferase assay to characterise the molecular mechanism by which PARP16 regulates cardiac function. RESULTSHuman heart failure samples showed reduced PARP16 expression. PARP16 expression was also significantly reduced in models of heart failure, including the hearts of isoproterenol-treated C57B/L6 mice and phenylephrine-treated primary cardiomyocytes. PARP16-deficient NRCMs showed signs of pathological remodelling. Whole-body, cardiac-specific, and inducible cardiac-specific PARP16 KO mice exhibited cardiac remodelling and dysfunction. In contrast, cardiac-specific PARP16-overexpressing mice were protected from iso-induced cardiac hypertrophy. Mechanistically, several hypertrophic signalling pathway genes are dysregulated in PARP16 knockout mouse hearts concomitant with upregulated NFAT1 transcriptional activity and nuclear translocation. PARP16 binds to and catalytically downregulates NFAT activity, thereby maintaining cardiac function. Mass spectrometry analysis showed that PARP16 is involved in ADP-ribosylation of NFAT1 at E398 and T533. Pharmacological inhibition of NFAT activation attenuates structural and functional abnormalities associated with PARP16 deficiency. CONCLUSIONSPARP16 binds to and inhibits NFAT1 activity to regulate cardiac function in mice, and its downregulation may activate NFAT1 signalling, leading to hypertrophy. In this manner, PARP16 plays a critical role in cardiac hypertrophy and failure and may serve as a potential therapeutic target for the treatment of heart failure.

Background: The clinical significance of sarcomere variants of uncertain significance (VUS) in hypertrophic cardiomyopathy (HCM) remains unclear, and VUS are currently regarded as clinically non-actionable despite their increasing prevalence. This study aimed to evaluate genotype?phenotype and genotype?outcome associations according to variant pathogenicity in patients with HCM, with a particular focus on the clinical relevance of sarcomere VUS. Methods: This multicenter retrospective cohort study included 438 patients with HCM who underwent next-generation sequencing-based genetic testing at two tertiary hospitals. Patients were classified into three groups: pathogenic or likely pathogenic (P/LP) variants, VUS, and no sarcomere mutations. Clinical characteristics, imaging phenotypes, and outcomes were compared across groups. The primary endpoint was a composite of cardiovascular death, aborted sudden cardiac death, appropriate implantable cardioverter-defibrillator therapy, and heart transplantation. Time-to-event analyses were performed using Kaplan-Meier methods and Cox proportional hazards models with Firth's penalized partial likelihood approach. Results: P/LP variants were identified in 171 patients (39.0%) and sarcomere VUS in 159 patients (36.3%). Patients with VUS demonstrated intermediate clinical and phenotypic features between P/LP carriers and genotype-negative patients. Kaplan?Meier analysis showed a graded difference in event-free survival across variant classifications. While VUS were not independently associated with adverse outcomes when modeled as a categorical variable, increasing pathogenicity from genotype-negative to VUS and P/LP variants was associated with a stepwise increase in risk of the primary endpoint (hazard ratio 2.05, 95% confidence interval 1.11?4.16 p=0.019). Identified VUS were preferentially enriched in Z-disc and giant sarcomere scaffolding proteins. Conclusion: Sarcomere VUS represent intermediate characteristics along a continuum of sarcomere dysfunction, associated with distinct phenotypic features and clinical outcomes compared with both P/LP variants and the absence of sarcomere mutations. These findings suggest that sarcomere VUS may not be entirely clinically neutral and should be interpreted within a broader genetic and structural context in patients with HCM.

Delivery of cells or vectors in advanced therapies is probably the major challenge for genetic disorders that affect a large part of the body such as Duchenne Muscular Dystrophy (DMD). Here, we describe a novel approach for systemic cell delivery based upon an implantable bio-scaffold composed of aligned polycaprolactone nanofibers coated with laminin, able to support adhesion and extensive proliferation of mesoderm cells both in vitro and when implanted subcutaneously in a DMD mouse model. The scaffold is rapidly vascularised leading to cell entering the circulation and colonising multiple distal organs, including distant skeletal muscles and heart. Cells survive in colonized muscles and differentiate into muscle fibres that produce well detectable levels of dystrophin and -sarcoglycan. These results are game changing for cell therapy, as they allow colonization of life essential but "difficult to reach" muscles such as diaphragm and heart while avoiding invasive catheterization. Once optimised, this approach will rapidly enter clinical experimentation for DMD, other muscular dystrophies, and possibly other genetic disorders of the mesoderm. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/715524v1_ufig1.gif" ALT="Figure 1"> View larger version (56K): org.highwire.dtl.DTLVardef@11dfd34org.highwire.dtl.DTLVardef@1da6599org.highwire.dtl.DTLVardef@14427f0org.highwire.dtl.DTLVardef@19a242a_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstractC_FLOATNO Study design and therapeutic outcome. Muscle biopsies were obtained from Duchenne muscular dystrophy (DMD) patients to isolate human DMD mesangioblasts (DMD-hMabs). Cells were genetically corrected using a lentivirus carrying a snRNA able to induce exon skipping (U7snRNA), generating U7-hMabs (1). U7-hMabs were seeded onto laminin-coated polycaprolactone (Lam-PCL) nanofiber scaffolds and implanted into the back muscle of DMD-NSG mice. This platform enabled systemic distribution of hMabs cells through circulation, resulting in engraftment across multiple muscle groups, including tibialis anterior, triceps, diaphragm and heart. C_FIG

BackgroundPersistent neurohormonal activation is a key driver of maladaptive remodeling and disease progression in heart failure (HF). Sodium-glucose cotransporter 2 inhibitors (SGLT2is) confer robust renoprotective effects in HF; however, the extent to which these benefits involve modulation of renal neurohormonal activity remains unclear. We hypothesized that SGLT2i-mediated renoprotection in HF is associated with attenuation of excessive renal neurohormonal activation. MethodsMale rats with myocardial infarction-induced HF and sham controls were fed standard chow or chow containing empagliflozin (EMPA, 300 mg/kg) for four weeks, followed by assessment of renal inflammatory and neurohormonal markers. Parallel in vitro studies in THP-1 macrophages and HK-2 proximal tubule cells evaluated the direct effects of EMPA on norepinephrine (NE)-dependent tubular inflammatory signaling. ResultsHF rats displayed higher renal cortical renin gene expression and angiotensin II concentrations, which remained unaffected by EMPA. Conversely, EMPA normalized the elevated urinary NE excretion and renal cortical NE content observed in HF rats. Given the inflammatory role of sympathetic hyperactivity, we assessed renal macrophage polarization. EMPA-treated HF rats showed reduced expression of pro-inflammatory markers (Tnf, Ccr2, Nos2, Il-6) and increased expression of markers associated with a reparative macrophage profile (Arg1, Mrc1, CD163), supported by higher CD206 macrophages in kidney sections. While EMPA did not directly alter THP-1 macrophage activation in vitro, it significantly reduced NE-induced SGLT2 expression and interleukin-6 (IL-6) release by HK-2 human proximal tubule epithelial cells. ConclusionThese findings support a model in which SGLT2 inhibitors confer renoprotection in HF by suppressing renal sympathetic hyperactivity, independently of the intrarenal renin-angiotensin system, thereby disrupting a maladaptive renal neuro-epithelial-immune axis and promoting a reparative macrophage phenotype. CLINICAL PERSPECTIVE Whats new?O_LIThis study identifies a renal neuro-epithelial-immune axis underlying empagliflozin-mediated renoprotection in heart failure. C_LIO_LIEmpagliflozin reduces renal cortical and urinary norepinephrine levels in heart failure without altering intrarenal renin-angiotensin system activity, revealing a distinct neurohumoral target of SGLT2 inhibition. C_LIO_LIThis sympatholytic effect is associated with a shift in renal macrophages toward a reparative (M2) phenotype, without changes in total macrophage abundance. C_LIO_LIEmpagliflozin blocks norepinephrine-induced SGLT2 upregulation, limiting proximal tubular glucose reabsorption and IL-6 production, and linking sympathetic signaling to renal inflammation. C_LI What are the clinical implications?O_LIOur findings provide a mechanistic basis for the additive cardiorenal benefits of SGLT2 inhibitors in heart failure, beyond conventional RAS-directed therapies. C_LIO_LITargeting renal sympathetic-driven inflammation may help preserve kidney function and attenuate the progression of cardiorenal syndrome. C_LIO_LISuppression of a renal neuroinflammatory pathway may help explain the early and sustained benefits of SGLT2 inhibitors across heart failure phenotypes, including nondiabetic patients. C_LI

Rationale: Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous syndrome with substantial unmet diagnostic and therapeutic needs. Circulating lipid metabolism is increasingly implicated in HFpEF pathophysiology but has not been systematically leveraged for molecular stratification. Objective: To determine whether plasma lipidomics can identify molecular phenogroups of HFpEF associated with distinct clinical characteristics and outcomes. Methods and Results: Untargeted plasma lipidomics was performed in non-HF subjects and HFpEF patients from a primary Belgian cohort and an independent Canadian cohort (n=177 in each cohort). In the Belgian cohort, 235 unique lipids spanning 19 subclasses were annotated, including 96 significantly associated with HFpEF (q<0.02). Unsupervised analyses revealed marked lipidomic heterogeneity, with a distinct HFpEF subgroup separable from non-HF subjects. Hierarchical clustering identified three phenogroups with divergent lipid profiles and clinical features. One phenogroup exhibited severe atrial dysfunction, congestion-related biomarkers, elevated indices of cardiac and liver fibrosis, and markedly reduced survival, a second was characterized by prominent metabolic syndrome features, and a third by preserved renal function. Cross-cohort comparison using a supervised classifier trained on 158 shared lipids confirmed analogous lower-risk phenogroups in the Canadian cohort, while the high-risk phenotype was underrepresented. A signature of 10 lipids across six subclasses, including long-chain acylcarnitines, ether phosphatidylcholines, and oxidized sphingomyelins, discriminated the high-risk group and correlated with markers of disease severity. Conclusion: Our findings demonstrate that HFpEF comprises metabolically distinct patient subgroups across cohorts, revealing specific lipidomic dysfunctions that deepen our understanding of HFpEF heterogeneity and underlying pathophysiology.

Aims: Dynamic left ventricular outflow tract obstruction (LVOTO) is a hemodynamically significant complication following transcatheter aortic valve replacement (TAVR) that remains difficult to predict with conventional transthoracic echocardiography (TTE). We examined whether a deep learning (DL) model developed for LVOTO detection in hypertrophic cardiomyopathy (HCM) could predict post-TAVR LVOTO from pre-TAVR TTE in patients with severe aortic stenosis (AS). Methods and Results: In this retrospective study of 302 consecutive patients undergoing TAVR for severe AS, a pre-trained DL model was applied to pre-TAVR TTE to generate a patient-level DL index of LVOTO (DLi-LVOTO; range 0-100). Post-TAVR LVOTO was defined as a peak pressure gradient [&ge;]30 mmHg on follow-up TTE. Logistic regression and receiver operating characteristic analyses assessed the association and discriminative performance of DLi-LVOTO. Pre-TAVR LVOTO was present in 32 patients (10.6%) and post-TAVR LVOTO in 35 (11.6%). Follow-up TTE was performed at a median of 47 days (IQR 37-63) after TAVR, with the majority of TTE (216 of 302, 71.5%) performed within 2 months. DLi-LVOTO was significantly higher in patients with LVOTO at both pre- and post-TAVR TTE (all p<0.001). In multivariable analysis, DLi-LVOTO remained independently associated with post-TAVR LVOTO even after adjusting for conventional TTE parameters and pre-TAVR LVOTO (adjusted OR 1.29, 95% CI 1.06-1.56 per 10-score increase, p=0.011), with an AUROC of 0.78 (95% CI 0.72-0.85). Among patients without pre-TAVR LVOTO, DLi-LVOTO retained independent predictive value (adjusted OR 1.56, 95% CI 1.19-2.06, p=0.001; AUROC 0.84, 95% CI 0.77-0.91). Conclusion: A DL model originally trained in HCM patients independently predicts post-TAVR LVOTO from pre-TAVR TTE, including in patients without pre-existing LVOTO, suggesting it captures hemodynamic features beyond conventional echocardiographic assessment.

BACKGROUND: Guidelines recommend aortic valve replacement (AVR) in patients with severe aortic regurgitation (AR) based on progressive changes in left ventricular (LV) function or size. We aimed to reassess the clinical relevance of current guideline recommendations pertaining to traditional echocardiographic measurements in routine practice. METHODS: Retrospective analysis of patients with severe AR who underwent serial echocardiographic follow-up over at least 18 months. The composite outcome was symptom-driven AVR, acute heart failure hospitalization, or death. We used a joint modelling approach to handle within-subject correlation and censoring. RESULTS: The cohort consisted of 140 patients, with a median follow?up of 93 months (interquartile range 58?130). LV end-systolic (LVESD) and fractional shortening (FS) showed a small but statistically significant longitudinal trend, while LVEDD did not. Changes in all three parameters in parallel joint models adjusted for age and gender were consistently associated with increased risk of the composite event. Each 1?mm increase in LVESD and LVEDD was associated with a 6% and 5% increase in risk, respectively; each 1% decrease in FS corresponded to a 12% increase in risk. Only 8 (5.7%) of patients were predicted to exceed the guideline-recommended LVEDD threshold of 65 mm over 10 years. Age at onset was also a significant risk factor, with each decade increasing risk by 65% for each of the three parallel joint models. CONCLUSIONS: LV parameters show modest changes over time, despite holding strong prognostic value in patients with severe AR. LVEDD, while associated with overall risk, does not predictably or significantly dilate over time in most patients. AVR decisions should be based on comprehensive clinical and volumetric assessment rather than waiting for simple linear progression to guideline cutoffs.

Background: Detection of disease progression is key to personalize treatment strategies in transthyretin cardiomyopathy (ATTR-CM), particularly with emerging therapies. Echocardiography can detect subtle longitudinal changes but is limited by operator dependence. This study evaluates agreement and reproducibility of fully automated, AI-assisted echocardiographic measurements under real-world conditions. Methods: This retrospective study included 62 patients with ATTR-CM undergoing 178 serial annual echocardiograms assessed by a reference cardiologist, a second cardiologist, a novice reader, and a fully automated AI algorithm (Us2.ai). Interrater agreement was assessed using Bland-Altman analysis and intraclass correlation coefficients (ICCs). Intrarater variability for human readers was derived from repeated blinded measurements, with limits of agreement (LoA = mean difference +/- 1.96 x SD) defining the smallest detectable change. AI repeatability was assessed using within-study pairwise differences. Results: AI showed moderate agreement with the reference cardiologist for IVSd and LVEDV (ICC 0.65 and 0.51), with biases of -1.9 mm and -39 mL, respectively. Interrater agreement between cardiologists was good (ICC 0.79 and 0.84) with minimal bias (-0.2 mm and +3 mL). Intrarater variability was moderate to excellent for both cardiologists (LoA 3.0 mm and 43 mL for the reference cardiologist; 2.7 mm and 31 mL for the second cardiologist). AI demonstrated comparable repeatability (LoA 3.6 mm and 37 mL), while the novice showed higher variability (5.1 mm and 61 mL). Conclusion: AI-based measurements demonstrated repeatability comparable to experienced cardiologists. Despite moderate agreement and systematic differences in volumetric assessments, their reproducibility supports automated analysis for longitudinal echocardiographic monitoring.

Background and Aims Despite treatment, patients with established atherosclerotic cardiovascular disease (ASCVD) are at high risk of recurrent events. Existing clinical risk scores for recurrence provide only moderate predictive performance and rely largely on the same conventional risk factors used to predict disease onset. Proteomics is a promising source of new biomarkers but the technologies need focused use cases in order to achieve utility and implementation. We aimed to determine whether plasma proteomics improves prediction of recurrent cardiovascular events beyond established clinical risk models in secondary prevention in a population-scale cohort. Methods Plasma proteomic profiles from ~9,300 participants in the UK Biobank with established ASCVD at baseline were analysed using machine learning methods to derive and evaluate proteomic predictors of recurrent cardiovascular events. The top performing model comprised proteins with non-zero weights (full protein score). Predictive performance of the proteomic predictors, an established clinical risk score (SMART2), and their combination was evaluated across six pre-defined testing datasets representing multiple ethnic and geographic groups. A parsimonious set of proteins with existing clinical-grade enzyme-linked immunosorbent assays (ELISAs) available was then derived. Results The full protein score achieved higher performance for recurrent ASCVD than the SMART2 risk score across all ethnic and geographic subgroups (mean C-index 0.743 vs 0.653). Adding the full protein score to SMART2 improved discrimination, with the largest increase in White Irish participants ({Delta}C-index, 0.140; 95% CI, 0.074-0.205; P<0.001). However, adding SMART2 to the protein score provided minimal additional value. The parsimonious score preserved most of the discrimination of the full protein model with C-indices of the recurrent ASCVD risk model comprising age, sex and the parsimonious protein score being nearly identical to the full protein model in the largest testing set (0.723 vs 0.728 for White British in England and Wales). The parsimonious protein score showed a marked gradient of risk with the top, middle and bottom quintiles showing 10-year recurrent ASCVD rates of ~27.4%, ~9.6% and ~2.4%, respectively. Conclusions In patients with established ASCVD, plasma protein measurements substantially improved prediction of recurrent events beyond conventional clinical risk factors, supporting their potential as a complementary tool to guide secondary prevention of cardiovascular disease.

BackgroundIndividuals with JAK2V617F-mutant myeloproliferative neoplasms or clonal hematopoiesis of indeterminate potential have a markedly increased risk of cardiovascular disease, yet the mechanisms by which mutant blood cells drive vascular and cardiac dysfunction remain incompletely understood. Although the thrombopoietin (TPO) receptor MPL is central to hematopoiesis and is expressed in vascular endothelial cells (ECs), its role in JAK2V617F-associated cardiovascular complications is unknown. Methods and ResultsWe generated chimeric mice with JAK2V617F-mutant blood cells and wild-type endothelium by bone marrow transplantation and challenged them with a high-fat/high-cholesterol diet to model cardiometabolic stress. These mice developed a distinct cardiovascular phenotype characterized by microvascular disease, increased left ventricular mass, and relatively preserved left ventricular ejection fraction. Histological analysis revealed coronary arteriole stenosis, perivascular fibrosis, reduced microvascular density, and endocardial injury, without evidence of epicardial coronary stenosis or myocardium infarction. Single-cell RNA sequencing revealed activation of inflammatory, stress-response, and endothelial-to-mesenchymal transition gene signatures in ECs, most prominently within the endocardial ECs. Immunohistochemistry identified MPL expression predominantly in endocardial ECs. TPO/MPL signaling was upregulated in endocardial ECs in mice with JAK2V617F-mutant hematopoiesis, and treatment with an anti-MPL neutralizing antibody markedly improved cardiac pathology, restored endocardial integrity, and increased coronary microvascular density despite persistent systemic inflammation. ConclusionsJAK2V617F-mutant hematopoiesis induces coronary microvascular dysfunction. Endocardial ECs represent a key cellular target under cardiometabolic stress, and endocardial MPL signaling constitutes a potential targetable pathway in JAK2V617F-associated cardiovascular disease. Graphic Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=122 SRC="FIGDIR/small/715884v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@1b0c2d7org.highwire.dtl.DTLVardef@1c7da20org.highwire.dtl.DTLVardef@1c19af9org.highwire.dtl.DTLVardef@1a588b3_HPS_FORMAT_FIGEXP M_FIG C_FIG Key PointsO_LIJAK2V617F-mutant hematopoiesis induces cardiac microvascular disease C_LIO_LIMPL is expressed in endocardial ECs and MPL inhibition restores endocardial integrity and improves cardiac microvascular function C_LI

Severe forms of inflammation-induced acute and chronic myocarditis have a poor prognosis. Promising therapeutic efforts focused on monoclonal antibodies (mAbs) inhibiting inflammation-inducing molecules. However, most mAbs target only one or a limited number of such molecules. Since inflammation involves multiple redundant pathways, we postulated that an mAb inhibiting multiple inflammatory pathways would be a potent therapeutic agent. We initially tested the commercially available anti-natural killer (NK) cell mAb (anti-NK1.1), which binds a receptor expressed on NK cells and depletes them. Since NK cells are key cellular orchestrators of inflammation, by reducing their number, we aimed to inhibit multiple inflammatory pathways. Our initial studies demonstrated that administration of this antibody significantly improved myocardial outcomes in mouse models of acute myocardial infarction and of heart failure. Since NK1.1 is not expressed in human cells, we built on these promising preclinical results by developing a novel mAb targeting CD160 on human NK cells for evaluation as an immunosuppressive therapy. We found that the anti-CD160 mAb depletes both murine and human NK cells. We also found that, while CD160+ cells were largely present in the NK population, they also occurred among CD8+ and {gamma}/{delta} T cell subsets in human cells. Anti-CD160 therapy entirely prevented the deterioration of the myocardial function of mice with autoimmune-induced acute myocarditis. This outcome suggests our novel approach for inhibiting multiple inflammatory pathways may provide a potent strategy for improving outcomes of inflammation-driven myocarditis, as well as of other inflammation-driven diseases. Key PointsO_ST_ABSQuestionC_ST_ABSCan the depletion of CD160+ cells prevent autoimmune-induced myocarditis? FindingsIn this study we found that CD160 is expressed by mouse and human natural killer cells and other subtypes of cytotoxic T cells, and that a monoclonal antibody targeting CD160 depletes NK cells. In a preclinical model of experimental autoimmune myocarditis, administration of the anti-CD160 monoclonal antibody prevented myocardial dysfunction and systemic inflammation. MeaningOur results are compatible with the hypothesis that early autoimmune-induced myocardial dysfunction is promoted by CD160+ cells, which elevate inflammation-induced circulating factors (or factors released by tissue-resident cytotoxic immune cells) that cause myocardial dysfunction in the absence of myocardial necrosis or fibrosis, and further, that targeting CD160+cells with a mAb that depletes NK cells (and probably CD160 expressing cytotoxic T cells) entirely prevents the deterioration of myocardial function in such mice. This outcome suggests our novel approach for inhibiting multiple inflammatory pathways may provide a potent strategy for improving outcomes of inflammation-driven myocarditis, as well as of other inflammation-driven diseases.

BackgroundVentricular assist devices (VADs) are used as treatment for end-stage heart failure in children and adults. We previously demonstrated decreased mitochondrial function and changes in cardiolipin, a mitochondrial phospholipid, in explanted pediatric and adult failing hearts. In this study, we tested the hypothesis that VAD unloading of failing hearts leads to positive changes in myocardial cardiolipin in both pediatric and adult hearts. MethodsVentricular tissue was collected from the same patient at time of VAD implantation and at transplant. Ejection fraction (EF), left ventricular internal diameter at end-diastole (LVIDd) and brain natriuretic peptide (BNP) were assessed pre- and post-VAD. Cardiolipin species from paired VAD core and explants were quantified using liquid chromatography mass spectrometry. Mitochondrial respiration was measured in ventricular tissue pre- and post-VAD in paired pediatric samples using the Oroboros Oxygraph-2k. ResultsVAD support led to increased EF and decreased LVIDd and BNP. The predominant cardiolipin species in cardiac mitochondria, tetralinoleoylcardiolipin, was positively remodeled in pediatric post-VAD myocardium, while adult post-VAD myocardium demonstrated significantly increased total cardiolipin and decreased oxidized cardiolipin but did not demonstrate the tetralinoleoylcardiolipin remodeling seen in pediatric hearts. In pediatric patients, VAD support resulted in significant increases in Complex I+II activity, and a trend toward increases in Complex I activity. ConclusionOur data demonstrate age-related differences in VAD-associated cardiolipin remodeling and suggest that improved mitochondrial function in pediatric VAD-supported hearts could be related to increased tetralinoleoylcardiolipin.

Right ventricular failure (RVF) is a serious disease with a high mortality but no effective pharmacologic treatments. We reported RVF was reversed by chronic treatment with an 1A-adrenergic receptor (1A-AR) agonist. Recent studies suggest mitochondrial dysfunction contributes to RVF. Therefore, we investigated if reversal of RVF by chronic 1A-AR agonist treatment involved improved mitochondrial function. A mouse model of RVF caused by pulmonary artery constriction (PAC) for 2 wk was chronically treated for a further 2 wk. with a low dose of the 1A-AR agonist A61603 (10 ng/kg/day) or vehicle (no drug control). RV dysfunction was assessed from the fractional shortening of the RV outflow tract (RVOT FS). RVOT FS for sham controls (46.5 {+/-} 1.3 %, n = 9) was reduced 4 wk after PAC (27.6 {+/-} 1.5 %, n = 13, P < 0.0001), but was higher after PAC plus 2 wk A61603 treatment (34.5 {+/-} 0.6 %, n = 14, P < 0.001). RV myocardial respiration rate (O2 consumption) for sham controls (776 {+/-} 51 pM/s/mg, n = 9) was reduced 4 wk after PAC (493 {+/-} 28 pM/s/mg, n = 15, P <0.0001), but was higher after PAC plus 2 wk A61603 treatment (634 {+/-} 30 pM/s/mg, n = 11, P <0.05). RV myocardial ATP level for sham controls (3.3 {+/-} 0.1 mM, n = 10) was reduced 4 wk after PAC (1.9 {+/-} 0.1 mM, n = 6, P < 0.0001), but was higher after PAC plus 2 wk A61603 treatment (2.6 {+/-} 0.13 mM, n = 7, P < 0.01). In conclusion, reversal of RVF after chronic A61603 treatment involved reversal of mitochondrial dysfunction. Consistent with our previous studies, this study suggests that the 1A-AR is a therapeutic target to treat RVF. HighlightsRV failure is reported to involve mitochondrial dysfunction which might impair RV contraction by decreasing cardiomyocyte ATP level. Using the pulmonary artery constriction model of RV failure, we found that chronic treatment with an 1A-adrenergic receptor agonist increased RV myocardial respiration rate, increased RV myocardial ATP level, and increased RV function. These findings suggest that the 1A-adrenergic receptor is a therapeutic target for treating RV failure, and that the mechanism involves improved RV cardiomyocyte bioenergetic status.

BackgroundPulmonary arterial hypertension (PAH) is a progressive disease marked by vascular remodeling, elevated pulmonary pressures, and right ventricular failure. Current therapies are mainly vasodilatory, underscoring the need for treatments targeting additional pathways. Sodium-glucose cotransporter-2 (SGLT2) inhibitors, initially used for diabetes, have demonstrated cardiovascular benefits. AimsThis systematic review and meta-analysis evaluated the effects of SGLT2 inhibitors in animal models of PAH, focusing on pulmonary hemodynamics and right ventricular function. MethodsPubMed, Embase, Web of Science, and Scopus were searched for preclinical studies reporting mean pulmonary artery pressure (mPAP), right ventricular systolic pressure (RVSP), right ventricular hypertrophy index (RV/LV+S), tricuspid annular plane systolic excursion (TAPSE), or pulmonary artery acceleration time (PAAT). Random-effects meta-analyses were performed using R. ResultsNine studies were included. SGLT2 inhibitors were significantly associated with lower mPAP (WMD -9.79 mmHg), RVSP (WMD -14.81 mmHg), and RV/LV+S (WMD -0.10). They were also associated with higher indices of right ventricular function, including TAPSE (WMD 0.53 mm) and PAAT (WMD 6.39 ms). ConclusionIn preclinical models of PAH, SGLT2 inhibitor treatment was associated with favorable hemodynamic and structural parameters. Further research is needed to clarify their translational potential and long-term safety.

BACKGROUNDMyocarditis is an inflammatory cardiac disease in which Th17-driven immune responses contribute to progression toward dilated cardiomyopathy and heart failure. Current therapies mainly rely on corticosteroids but lack specificity, while the role of miR-721, synthesized by Th17 cells, remains largely unexplored in disease pathogenesis. METHODSWe characterized the presence of mmu-miR-721 and its human homolog hsa-RNA-Chr8:96 in extracellular vesicles (EVs) secreted by Th17 cells from IL-17eGFP mice with experimental autoimmune myocarditis (EAM) and myocarditis patients. MxCre-Ppargfl/fl mice and luciferase reporter assays were used to validate the target genes of miR-721 and hsa-RNA-Chr8:96, respectively. The functional role of miR-721 in EAM was investigated by lentiviral vectors overexpression and inhibition using miRNA sponge molecules. Th17 responses and heart inflammation were assessed and echocardiography was performed after in vivo blockade of mmu-miR-721 in EAM mice. RESULTSBoth mmu-miR-721 and hsa-RNA-Chr8:96 were encapsulated in EVs and secreted by Th17 cells of mice and patients with myocarditis. Overexpression of mmu-miR-721 in draining-lymph node cells from EAM mice inhibited Pparg transcription, leading to increased ROR{gamma}t and IL-17 expression and promoting Th17 differentiation. In contrast, in the absence of Pparg, a target of miR-721, no differences in ROR{gamma}t expression were observed, indicating that miR-721 promotes Th17 responses through repression of Pparg. Human PPARG was validated as a target gene of hsa-RNA-Chr8:96 and its overexpression in peripheral blood leukocytes downregulated PPARG mRNA levels, suggesting similar pathways involved in human pathology. In vivo blockade of mmu-miR-721 increased Pparg expression, reducing ROR{gamma}t and IL-17 activation in T cells and leading to decreased leukocyte infiltration in the heart and improved cardiac function. CONCLUSIONSmiR-721 is released by Th17 cells in EVs and promotes Th17 responses during myocarditis through repression of PPAR{gamma}, identifying this miRNA as both a mechanistic driver of disease and a potential therapeutic target. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=168 SRC="FIGDIR/small/713340v1_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@1a69953org.highwire.dtl.DTLVardef@9c36bdorg.highwire.dtl.DTLVardef@1cdce4dorg.highwire.dtl.DTLVardef@a34715_HPS_FORMAT_FIGEXP M_FIG C_FIG Novelty and significanceO_ST_ABSWhat is known?C_ST_ABSO_LImiR-721 and its human homolog are upregulated in the plasma of mice and humans with myocarditis C_LIO_LITh17 cells synthesize miR-721 C_LIO_LIMmu-miR-721 targets Pparg mRNA C_LI What new information does this article contribute?O_LImiR-721 is sorted into extracellular vesicles in the context of acute myocarditis C_LIO_LImiR-721 enhances Th17 differentiation via the Pparg/Rorc double inhibitory axis. C_LIO_LIHsa-RNA-Chr8:96 targets human PPARG mRNA for degradation, inhibiting its expression C_LIO_LIBlockade of miR-721 dampens acute myocarditis development in vivo C_LI This study reveals a novel miRNA-based therapeutic strategy to inhibit Th17 responses and treat myocarditis. Using the experimental autoimmune myocarditis model, the authors unravel the mechanisms by which mmu-miR-721 can enhance Th17 responses and show how targeting this regulatory molecule could ameliorate the progression of the disease. Remarkably, this regulatory axis is suggested to be present in humans as well, since PPARG gene is validated as a target gene for hsa-RNA-Chr8:96. These findings highlights the potential of miR-721 not only as a diagnostic tool but also as a cell-specific therapeutic target to control Th17 responses in the clinical setting.

Background: Women with severe aortic stenosis (AS) are diagnosed later and experience poorer outcomes than men, partly because clinical approaches rely on 2D, valve-centric thresholds derived from male-predominant cohorts that underutilize information from 3D left ventricular (LV) geometry. We hypothesize that a sex-specific computational framework integrating statistical shape analysis (SSA) of pre-TAVR CT with machine learning would improve prediction of 1-year LV mass regression (LVMR). Objective: To develop a computational framework leveraging 3D LV geometry and evaluate whether it improves sex-specific prediction of 1-year LVMR after TAVR. Methods: We studied 339 patients with severe AS who underwent TAVR from 2013 to 2020 and had pre-TAVR CT and 1-year post-TAVR echocardiography. LV geometries were segmented into digital twins, and shape modes predictive of LVMR were extracted using SSA and partial least squares. These modes were incorporated into support vector regression models and compared with conventional echocardiographic predictors, including pre-TAVR LVEF, LVMI, and E/A ratio. Performance was assessed using RMSE and R^2. Results: After one year, 65% of patients showed positive LVMR, with median regression of approximately 10%; regression was significant overall and within each sex (p<0.001) and similar between sexes (p=0.99). Predictive shape modes differed by sex (p<0.01), with women showing more localized variation and men broader geometric gradients. Sex-specific shape modes outperformed general modes and clinical metrics, particularly in women (R^2=0.80, RMSE=0.09 vs. R^2=0.59, RMSE=0.13; clinical-only baseline R^2=0.16, RMSE=0.22). In men, sex-specific modes also performed strongly (R^2=0.89, RMSE=0.08). Conclusion: In severe AS, 3D LV geometry predicts post-TAVR reverse remodeling more accurately than conventional metrics and may improve risk stratification, particularly in women.