Nature Cardiovascular Research

Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous cardiometabolic syndrome in which the molecular programs linking metabolic stress to myocardial remodeling and diastolic dysfunction remain incompletely defined. We integrated ventricular RNA sequencing with pathway activity profiling, transcription factor inference, cell-type enrichment, phenotype association, elastic-net severity modeling, cross-lab murine validation, and human proteomic comparison to define the systems-level architecture of remodeling in the db/db + aldosterone mouse model of cardiometabolic HFpEF. HFpEF hearts exhibited a distinct transcriptomic state characterized by coordinated upregulation of collagen organization, TGF{beta} signaling, inflammatory response, and NF{kappa}B signaling, with reduced ion-channel activity and smaller shifts in oxidative phosphorylation, excitation-contraction coupling, and mechanotransduction. These pathway programs were linked to left ventricular hypertrophy and diastolic dysfunction and were accompanied by enrichment of fibroblast, myofibroblast, and macrophage signatures that tracked the same disease dimensions. Gene-level prioritization identified extracellular matrix, inflammatory, and mechanotransduction-associated candidates linked to disease severity, while transcription factor analysis revealed a broader multi-regulator architecture associated with fibrotic, inflammatory, and stress-responsive remodeling. Elastic-net modeling further showed that phenotype-derived remodeling severity was captured in an exploratory nested cross-validation framework primarily by transcription factor and fibro-inflammatory cell-program features, whereas pathway-summary scores added little incremental predictive information. In an independent HFD+L-NAME cohort, pathway remodeling showed selective reproducibility, and cross-species comparison demonstrated that concordance with human HFpEF proteomic subgroups was pathway selective rather than global. Together, these findings define a multilevel systems architecture of cardiometabolic HFpEF remodeling and support mechanistic prioritization and pathway-matched preclinical model selection.

Heart failure with preserved ejection fraction (HFpEF) is widely linked to endothelial dysfunction, yet the molecular pathways translating cardiometabolic stress into microvascular remodeling remain poorly defined. Here, we identify endothelial YAP/TAZ signaling as a mechanistic regulator of sex-divergent vascular responses in HFpEF. Plasma proteomics from the UK Biobank revealed elevated circulating YAP1 levels associated with heart failure and increased mortality, particularly in male patients, where YAP1 coincided with increased levels of the endothelial activation marker ESM1. In a hypertensive cardiorenal mouse model, endothelial YAP/TAZ deletion preserved cardiac function, whereas endothelial TAZ gain-of-function aggravated disease. Under cardiometabolic stress (TNF and high glucose), endothelial cells exhibited sex-specific rewiring of YAP/TAZ-dependent transcriptional programs. Male endothelial cells showed increased extracellular YAP1 release, angiogenic instability with impaired extracellular matrix remodeling, whereas female cells adopted an immune-primed, stress-adaptive phenotype. Mechanistically, cardiometabolic stress uncoupled canonical YAP-TEAD transcription and engaged alternative cofactors, including VGLL3 and VGLL4, thereby reshaping the endothelial secretome and propagating sex-divergent microvascular remodeling. These findings identify endothelial YAP/TAZ rewiring as a molecular switch that converts cardiometabolic stress into sex-divergent microvascular remodeling in HFpEF and connect this process to circulating YAP1 and ESM1 in patients.

BackgroundMetabolic dysfunction-associated steatohepatitis (MASH) is emerging as a risk factor of cardiometabolic diseases, including the atrial fibrillation (AF) - the most common sustained arrhythmia. Given that the liver is a major source of inflammatory mediators, lipids, and hepatokines under metabolic stress, we hypothesized that hepatocyte-derived factors in MASH may accelerate atrial remodeling and arrhythmogenesis. MethodsAnalysis of the Atherosclerosis Risk in Communities (ARIC) visit 5 cohort was performed to determine the association between the FIB-4 index - a classic indicator of liver fibrosis, and AF risk, with multivariable adjustment for common comorbidities. A murine model of MASH was induced using the GAN (Gubra-Amylin NASH) diet. Programmed intracardiac stimulation and echocardiography were performed to assess AF susceptibility and cardiac function. Calcium imaging, histology, flow cytometry, plasma proteomics, and single-nucleus RNA sequencing (snRNA-seq) analyses were employed to elucidate the role of recruited inflammatory macrophages via hepatocyte-derived osteopontin (OPN) in MASH-induced atrial remodeling. ResultsAnalysis of the ARIC cohort confirmed a higher cumulative incidence of AF and an elevated adjusted hazard ratio (HR) in patients with intermediate and high FIB-4 indices compared to individuals with low FIB-4 scores. MASH mice exhibited increased susceptibility to pacing-induced AF, accompanied by enhanced proarrhythmic calcium release events, atrial enlargement, and fibrosis, independent of ventricular dysfunction. Proteomics and snRNA-seq revealed that the hepatocyte-secreted OPN under MASH conditions promoted the differentiation and recruitment of TGFBR1+ inflammatory macrophages to the atria, leading to gasdermin D (GSDMD) activation - an effector of inflammasome signaling and consequent proarrhythmic atrial remodeling. Activation of the monocyte-derived pro-inflammatory TGFBR1+ macrophages was dependent on the OPN receptor CD44. Furthermore, the MASH-induced atrial fibroinflammatory milieu and enhanced AF susceptibility were mitigated through several strategies, including hepatocyte-specific Spp1 (encoding OPN) deletion, neutralization of circulating OPN, ablation of CD44 or GSDMD. ConclusionsThese findings establish a pathogenic role of the hepatokine osteopontin in driving activation and recruitment of TGFBR1+ inflammatory macrophages into the atria, leading to proarrhythmic atrial remodeling under MASH. Osteopontin-targeted therapy or GSDMD inhibition prevents AF, indicating a novel therapeutic strategy for liver disease-related atrial arrhythmogenesis. Clinical PerspectiveO_ST_ABSWhat is new?C_ST_ABSO_LIIn the ARIC cohort, metabolic dysfunction-associated steatohepatitis (MASH) is associated with increased risk of atrial fibrillation (AF) after adjusting for common comorbidities. Elevated levels of circulating osteopontin (encoded by SPP1) predict an increased risk of AF in patients with MASH-induced liver fibrosis. C_LIO_LIMASH enhances hepatocyte secretion of osteopontin, leading to expansion of myeloid cells and recruitment of inflammatory macrophages into atria. This liver-to-atrial inflammatory circuit promotes the development of a substrate conducive to AF, which can be attenuated by hepatocyte-specific Spp1 deletion or neutralizing anti-anti-osteopontin antibody treatment to eliminate the mediator, or ablation of inflammasome effector gasdermin D to correct the atrial response. C_LI What are the clinical implications?O_LIOsteopontin may serve as a biomarker for AF in MASH cohorts. C_LIO_LIAnti-osteopontin therapy through neutralizing antibodies may serve as a novel therapeutic strategy for liver disease-related atrial arrhythmia. C_LI

BK channels, coded by the Kcnma1 gene, integrate voltage and intracellular Ca2+ signals and are recognized for their roles in smooth muscle and neuronal excitability. However, their contribution to baseline cardiac physiology remains poorly defined. Here we uncover a fundamental function for BK channels in maintaining normal cardiac performance, independent of pathological stress. Using non-invasive echocardiography, transcriptional profiling, and mechanistic analyses, we demonstrate that Kcnma1 deletion disrupts ventricular function, and remodels metabolic and stress-response pathways. Transcriptomic profiling revealed selective downregulation of mitochondrial uncoupling proteins (UCPs) and suppression of the PGC-1/FOXO3a axis, without broad loss of oxidative phosphorylation components. Enhancing UCP expression restored cardiac performance, indicating that mitochondrial uncoupling and redox control constitute key downstream effectors of BK signaling. Together, these results identify a physiological role for BK channels in maintaining myocardial function and define a mitochondrial BK-UCP axis, critical for cardiac homeostasis.

The loss of smooth muscle cell (SMC) contractile phenotype contributes to various diseases including atherosclerosis. However, its metabolic basis is not entirely elucidated. Since the transforming growth factor beta (TGF{beta}) signaling is among principal regulators of SMC contractility, we studied metabolic regulation of TGF{beta} signaling in SMCs in vitro and atherosclerotic mouse models and human lesions. We found that TGF{beta} induced Ac-CoA synthetase 2 (ACSS2)-dependent Ac-CoA production, by suppressing pyruvate dehydrogenase kinase 4 (PDK4). This stabilized R-SMADs and TGF{beta} receptor 1, preserving SMC contractile phenotype. SMC-specific PDK4 knockout mimicked the effect of TGF{beta} signaling both metabolically and phenotypically, increasing glucose-derived synthesis of Ac-CoA and SMC contractile phenotype. SMC-specific Pdk4 knockout in ApoE knockout mice reduced atherosclerosis. Furthermore, human specimens demonstrated a strong correlation between PDK4 level and atherosclerosis severity. These findings indicate that continuous TGF{beta} signaling, critical to the maintenance of the normal SMC contractile state and is regulated by PDK4 and carbohydrate metabolism. TeaserReducing PDK4 metabolically restricts aortic plaque growth via TGF{beta}-dependent SMC contractility.

Chronic pressure overload induces cardiac hypertrophy and heart failure through coordinated alterations in proteome homeostasis, metabolism and sarcomere organisation. The muscle-specific -isoform of the nascent polypeptide-associated complex (skNAC) is essential for sarcomere assembly during development, but its role in adult hearts remains largely unknown. Here, we show that skNAC expression is reduced in hypertrophic cardiomyocytes, mouse models of pressure overload, and human hypertrophic hearts, in association with disease severity. Cardiomyocyte-specific skNAC deletion results in basal hypertrophy, systolic dysfunction, and premature death, and exacerbates pressure overload-induced heart failure. At the molecular level, skNAC associates with ribosomes and is required for sarcomere organisation maintenance, while its loss induces autophagy and ultrastructural defects. Integrated transcriptomic and proteomic analyses reveal early downregulation of metabolic gene expression despite increased abundance of corresponding proteins, indicating compensatory metabolic responses. Gain-of-function studies confirm a protective role against hypertrophy. Together, these data establish skNAC as a key regulator of cardiac proteome homeostasis and metabolic adaptation during pathological remodelling.

Advances in single-cell and spatial assays have revolutionized the scale and resolution of molecular tissue profiling. Here we present MetaPlaq, a multimodal atlas of human atherosclerotic arterial beds comprising over a million cells across single-cell transcriptomics, epigenomics and high-resolution spatial expression assays. We map granular cell states and disease-relevant transcriptional programs within the native tissue context of coronary arteries. Furthermore, we map cardiovascular GWAS signals to smooth muscle cells (SMCs) and endothelial cells (ECs) and uncover the cis-regulatory architecture governing their phenotypic transitions. Our comprehensive epigenomic reference allowed us to build cell-specific enhancer-gene link maps and multimodal gene regulatory networks (GRNs) underlying disease-relevant states such as osteogenic SMCs and ECs undergoing mesenchymal transition. We also integrate SMC and EC disease-associated gene sets with GRNs to nominate key transcription factors such as PRRX1, BNC2 and ELK3 regulating atherosclerosis-relevant transcriptional programs. Finally, we layer single-cell and spatial modalities to fine-map GWAS variants with improved cell and anatomical context. We highlight candidate cell-specific regulatory mechanisms at less characterized CAD loci, including FGD5 and MCF2L in ECs. Together, this atlas represents an important step towards fully interpreting genetic risk loci and informing new therapeutic strategies for cardiovascular disease.

Resilience to cardiac stress is essential for health, yet the relationship between cardiomyocyte (CM) stress response and local microenvironment remains unclear. Here, we combined MERFISH spatial transcriptome profiling with Cellouette, an improved cell segmentation method, to determine CM-microenvironment relationships in a mouse model of ventricular pressure overload. We report the shape, transcription profile, spatial organization, and physical connectivity for >400,000 cells across stressed and healthy tissues. Under stress, CMs adopted a spectrum of emergent transcriptional states, with advanced states marked by a metabolic and pro-fibrotic shift. To discover CM-environment relationships, we performed a network analysis of physical cell connectivity combined with cell-type-specific profiling. We found that pro-fibrotic CM progression was tightly linked to distinct local microenvironments, and CM metabolic shifts could be inferred from transcriptional patterns in neighboring non-CM cells, revealing microenvironmental imprints of disease. We thus provide a resource for understanding the heterogeneity of outcome during cardiac pressure overload. HighlightsO_LICellouette provides accurate segmentation for single-cell spatial transcriptomics in cardiac tissue. C_LIO_LIPressure overload creates spatial gradients of cardiomyocyte pro-fibrotic states. C_LIO_LICardiomyocyte pro-fibrotic progression is linked to changes in local cell composition and gene expression. C_LIO_LITranscriptional states of non-muscle cells predict metabolic state of adjacent cardiomyocytes. C_LI

The electrocardiogram (ECG) encodes the electrical activity of the heart across multiple timescales, yet standard clinical analysis collapses this rich signal into a handful of scalar measurements that discard most of the waveform's structure. Whether the frequency signals lost in this reduction carry heritable biological information relevant to cardiovascular disease risk remains unclear. Here we decompose resting 12-lead ECGs from 47,052 White British UK Biobank participants into 84 frequency-specific energy features using Daubechies-6 wavelet analysis across 12 leads and 7 decomposition levels, and perform independent genome-wide association analyses on each feature. We identify 67 independent loci and refine these to 101 high-confidence causal variants (posterior inclusion probability > 0.80) through Bayesian fine-mapping; associated loci converge on genes governing cardiac conduction and myocardial integrity, including SCN5A, TTN, KCNQ1, and DSP, alongside less-characterized cardiomyopathy candidates. SNP-based heritability estimates range from 0.03 to 0.26, with the strongest signals in mid-frequency bands (D6-D4, ~4-32 Hz) of Lead I and aVR, and strong inter-lead genetic correlations indicate a coordinated genetic architecture underlying the waveform. Integrating these features with FinnGen R12 cardiovascular phenotypes reveals genetic correlations reaching 0.56 with heart failure, driven predominantly by energy in the highest-frequency band (D1, 125-250 Hz), a spectral range routinely filtered from clinical ECGs and previously regarded as acquisition noise. These results reframe the electrocardiogram as a multi-frequency genetic phenotype, expand the set of cardiac loci discoverable from ECG data, and implicate high-frequency cardiac electrical activity as an underexplored dimension of cardiovascular disease risk.

Arterial restenosis following balloon angioplasty - a procedure performed to re-establish vessel patency in atherosclerotic cardiovascular disease - remains a major clinical challenge and a key barrier to durable revascularization. Endothelial denudation induced by angioplasty triggers an inflammatory cascade that drives vascular smooth muscle cell (VSMC) proliferation, migration, and phenotypic switching, culminating in neointimal hyperplasia and restenosis1. Human genetics-guided target discovery has proven more effective than non-guided approaches in revealing causal pathways of complex cardiovascular traits2. Genetic variants at Histone Deacetylase 9 (HDAC9) are a major risk factor for cardiovascular disease3,4 and is associated with increased carotid intima-media thickness and modulation of VSMC phenotype4. Here, using an experimental model of arterial injury that faithfully mirrors the vascular response to balloon angioplasty in humans, we show that HDAC9 drives maladaptive remodeling of the arterial wall following vascular injury.

Vascular endothelial cells respond to environmental forces to remodel vessels during development and to achieve homeostasis, and mis-regulated responses lead to vascular dysfunction and disease. The nucleus participates in force transduction to cell-matrix junctions via the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex that resides in the nuclear envelope, but how these forces are regulated and relayed is incompletely understood. We found that the LINC complex protein SUN2 is required for proper endothelial cell-matrix interactions that occur far from the nucleus and affect angiogenic expansion, vascular responses to flow, and barrier integrity. Endothelial cells lacking SUN2 had inappropriate flow responses and reduced expression of flow-mediated transcription factors in vitro and in vivo. Expression of several matrix and adhesion genes was reduced in SUN2-depleted cells, leading to defective extracellular matrix, dysmorphic focal adhesions resistant to dynamic turnover, and disturbed cell-matrix force distribution. Mechanistically, nuclear SUN2 affected dynamic regulation of the microtubule cytoskeleton that correlated with matrix metalloprotease-dependent barrier dysfunction. These findings indicate that nuclear SUN2 establishes and maintains blood vessel homeostasis by controlling microtubule-mediated effects on focal adhesion turnover and extracellular matrix properties, with implications for cardiovascular aging and diseases such as Marfan syndrome that affect vessel wall integrity.

Systemic amyloidosis is typically diagnosed only after irreversible organ damage has occurred, limiting the effectiveness of available therapies. Whether the disease is preceded by detectable molecular changes long before clinical presentation has remained unclear. Here, we leveraged population-scale plasma proteomics and longitudinal follow-up from the UK Biobank to investigate early circulating protein signatures associated with future diagnosis of amyloidosis. Among approximately 53,000 participants with proteomic profiling, we identified 61 individuals who developed amyloidosis up to 14 years after protein assessment. Differential expression and correlation analyses identified a seven-protein panel, including MYL3, MYBPC1, NT-proBNP, NPPB, FCRLB, IGFBP1, and FABP1, consistent with early cardiac stress and immune dysregulation. Time-to-event modelling demonstrated robust stratification of amyloidosis risk and timing. Importantly, a parsimonious subset of these proteins retained strong predictive performance, indicating that a reduced set of biologically informative markers is sufficient for risk stratification. Furthermore, these proteomic signals were not explained by pre-existing cardiac disease, clonal haematopoiesis, or related plasma cell disorders, indicating that they capture disease-specific biological processes preceding clinical diagnosis. Together, these findings show that amyloidosis is preceded by persistent plasma proteomic alterations, providing a framework for early risk stratification and insight into the preclinical biology of this under-recognised disease.

Cardiovascular disease remains the leading cause of mortality worldwide, yet substantial risk persists beyond traditional clinical and metabolic predictors. The immune system is a key mediator of this residual risk, but clinically scalable metrics of immune state are lacking. Here, we established the clinical and prognostic relevance of IMM-AGE, a system-level metric of immune aging derived from immune cell correlation structure. We developeda transcriptomic gene-ratio signature and optimized reduced-marker flow cytometry panels that accurately preserve IMM-AGE across blood fractions, platforms and cohorts. Applying these clinic-ready implementations across population-based and disease-specific datasets, we show that elevated IMM-AGE is consistently associated with cardiovascular phenotypes and disease. We leverage the UK biobank to show that incorporation of IMM-AGE into the PREVENT 10-year risk equation increase accuracy of risk stratification. We also show that in elderly patients undergoing transcatheter aortic valve replacement, baseline IMM-AGE independently predicted early maladaptive cardiac remodeling and one-year mortality. Finally, in the Baseline Health Study, a large longitudinal cohort, IMM-AGE stratified cardiovascular event risk among individuals with otherwise similar clinical profiles. Together, these findings establish immune aging as a transferable, biologically grounded risk dimension and support IMM-AGE as a practical tool for precision cardiovascular risk assessment.

Hypertrophic cardiomyopathy (HCM) is often characterized by a complex landscape of secondary compensatory changes, making it difficult to distinguish primary events triggered by the underlying genetic variants. Here, using patient-derived iPSC-engineered heart tissues cultured in conditions minimizing external stimuli, we identify the initial phenotype of the HCM inducing variant MYBPC3-Q1061X. We demonstrate that initially MYBPC3 haploinsufficiency leads to robust, muscle length-dependent hypercontractility with emerging diastolic dysfunction at higher contraction rates. This phenotype is entirely decoupled from early transcriptional and metabolic stress responses, as evidenced by physiological phenotype and metabolite and cell type-specific transcriptional profiles. Mathematical modeling reveals that the hypercontractile phenotype can be translated to adult cardiac muscle with a small change in myosin availability, amplified by inherent cooperativity within the sarcomere that is instrumental in enhancing the force and the speed of the contraction cycle. Despite the apparent calcium sensitization, these sarcomeric changes do not affect excitation-contraction coupling or calcium buffering in this proximal stage. These results suggest that the primary biophysical defect in MYBPC3-haploinsufficiency manifests as a latent mechanical hypersensitivity that precedes secondary cellular remodeling and functional instability. This initial phenotype provides a window for preventive therapeutic intervention before the onset of permanent cellular remodeling in the heart.

Blood-brain barrier (BBB) breakdown is a critical pathological event driving secondary brain injury and poor outcomes following intracerebral hemorrhage (ICH). However, the mechanisms governing acute BBB breakdown after ICH remain incompletely understood. Here we demonstrate that the Sphk1-S1P-S1PR3 signaling plays a pivotal role in this process. Sphk1 expression was significantly upregulated in the perihematomal endothelial cells of both ICH patients and mice, with levels positively correlating with BBB dysfunction severity and poor clinical outcomes. Using endothelial-specific genetic gain- and loss-of-function approaches, we found that Sphk1 knockdown attenuated BBB leakage, reduced hematoma volume and brain edema, preserved tight junction integrity, and improved neurological function at 1-day post-ICH, whereas Sphk1 overexpression exacerbated these pathological features. Mechanistically, transcriptomic profiling of perihematomal endothelial cells revealed that prior to its established role in Nlrp3-mediated pyroptosis, Sphk1 promotes early BBB breakdown by regulating the Bsg-MMP-9 axis. Endothelial-specific Bsg deletion completely abrogated the deleterious effects of Sphk1, confirming Bsg as an indispensable intermediary through which Sphk1 signals to MMP-9. ATAC-seq and dual-luciferase assays further demonstrated that Sphk1-generated S1P signals through S1PR3 to activate HIF-1, which directly binds the Bsg promoter to drive its transcription, ultimately promoting MMP-9-mediated tight junction degradation. These findings delineate a complete hierarchical signaling cascade from metabolic enzyme to transcriptional regulation and subsequent barrier injury, establishing the Sphk1-Bsg-MMP-9 axis as a promising therapeutic target for ICH. One sentence summaryThis work identifies an early and pivotal mechanism of blood-brain barrier breakdown after intracerebral hemorrhage, demonstrating that Sphk1-generated S1P signals through S1PR3 to activate HIF-1, which directly transactivates Bsg expression, leading to MMP-9-mediated tight junction degradation, thereby establishing a novel hierarchical axis with therapeutic potential.

BackgroundLong COVID postural orthostatic tachycardia syndrome (LCPOTS) is characterized by persistent orthostatic tachycardia and multiple constitutional symptoms, many of which suggest persistent inflammation. We sought to define mechanisms responsible for ongoing immune activation in LCPOTs and to determine if this is related to autonomic dysregulation. MethodsWe performed a case-control study of 25 patients with LCPOTS and 15 controls who recovered from COVID-19 without persistent autonomic sequelae. Peripheral blood mononuclear cells were analyzed by flow cytometry to quantify circulating CD3CD14 T cell-monocyte doublets, cytokine production, memory phenotype, mitochondrial ROS, and isolevuglandin (IsoLG)-adduct formation. Forster resonance energy transfer was used to assess T-cell receptor-HLA interactions within doublets. Single-cell RNA sequencing (scRNA-seq) was performed on a subset of participants, and autonomic phenotyping included orthostatic heart rate responses, heart rate variability, baroreflex sensitivity, and blood volume measurements. ResultsLCPOTS was linked to impaired cardiovagal function and greater autonomic symptom burden. It was also associated with roughly a threefold rise in circulating CD3CD14 doublets and enhanced T cell-monocyte interactions. These complexes demonstrated signs of genuine immune synapse formation and were enriched with effector-memory and TEMRA T-cell types. T cells in doublets produced higher levels of IFN-{gamma} and IL-17A, and the proportion of cytokine-producing doublets correlated with the severity of orthostatic tachycardia and total COMPASS-31 score. Monocytes from LCPOTS showed increased mitochondrial content, superoxide generation, and IsoLG-adduct accumulation, along with decreased expression of antioxidant genes, including those related to NFE2L2. ConclusionsOur findings suggest that ongoing immune activation contributes to LCPOTS pathogenesis. We propose that impaired cardiovagal regulation stimulates monocyte ROS production, promotes neoantigen formation, and T cell activation. This persistent immune response, together with disrupted mitochondrial function, likely contributes to the diverse symptoms linked to LCPOTS. Novelty and SignificanceO_ST_ABSWhat Is Known?C_ST_ABSO_LILong COVID postural orthostatic tachycardia syndrome is associated with persistent orthostatic tachycardia and disabling orthostatic intolerance symptoms after SARS-CoV-2 infection. C_LIO_LIImmune dysregulation and oxidative stress have been implicated in long COVID, but the cellular mechanisms linking inflammation to autonomic dysfunction are not well defined. C_LIO_LICirculating T cell: monocyte doublets are a recently recognized marker of ongoing immune activation. C_LI What New Information Does This Article Contribute?O_LIPatients with LCPOTS exhibit a marked increase in circulating CD3CD14 T cell-monocyte doublets. C_LIO_LIDoublet-associated T cells are enriched for inflammatory effector-memory/TEMRA phenotypes and produce IFN-{gamma} and IL-17A in proportion to orthostatic tachycardia and autonomic symptoms severity. C_LIO_LIImpaired cardiovagal activity, monocyte mitochondrial ROS, IsoLG-adduct formation, and suppression of antioxidant pathways identify a mechanistic axis linking oxidative injury to persistent immune activation in LCPOTS. C_LI Summary of Novelty and SignificanceThis study identifies a mechanistic link between impaired cardiovagal function, mitochondrial oxidative stress, and persistent immune activation in LCPOTS. We show that circulating CD3CD14 T cell-monocyte doublets are expanded in LCPOTS and form true immune synapses, as demonstrated by T-cell receptor-HLA proximity. These are enriched in inflammatory effector-memory/TEMRA T cells and are associated with increased IFN-{gamma} and IL-17A production that correlate with orthostatic tachycardia severity and symptom burden. We further identified increased mitochondrial ROS, accumulation of IsoLG adducts, and reduced antioxidant gene expression in monocytes, suggesting that oxidation-induced neoantigen formation sustains pathogenic T-cell engagement. Together, these findings move LCPOTS beyond a descriptive post-viral syndrome and define a biologically plausible immune mechanism with diagnostic and therapeutic implications. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=109 SRC="FIGDIR/small/26352776v1_ufig1.gif" ALT="Figure 1"> View larger version (68K): org.highwire.dtl.DTLVardef@12f15b0org.highwire.dtl.DTLVardef@38e9e9org.highwire.dtl.DTLVardef@84c229org.highwire.dtl.DTLVardef@1e72cae_HPS_FORMAT_FIGEXP M_FIG C_FIG

IntroductionAortic stenosis (AS) is characterised by progressive aortic valve (AV) leaflet fibrosis and calcification, yet no medical therapies exist to slow disease progression. AV interstitial cells (VICs) that differentiate into myofibroblasts are central drivers of fibrosis. The Ca2+-activated K+ channel KCa3.1 promotes pro-fibrotic signalling in several fibrotic diseases, however its role in AS remains unknown. MethodsKCa3.1 protein expression was examined in paraffin embedded tissue by Immunohistochemistry from control and AS valve tissue. VICs were isolated, cultured and phenotypically characterised as myofibroblasts from AV tissue obtained from patients with severe tricuspid AS undergoing surgical AV replacement (n=19). KCa3.1 mRNA and protein expression were assessed by qRT-PCR and immunohistochemistry, and functional channel activity confirmed using patch-clamp electrophysiology. The effects of transforming growth factor-{beta}1 (TGF{beta}1) stimulation and pharmacological inhibition with the selective KCa3.1 blocker senicapoc were examined. ResultsImmunoreactive KCa3.1 channels and smooth muscle actin were detected in both control and AS aortic valve tissue, localised to elongated, nucleated interstitial cells, with significantly higher expression observed in AS tissue compared to control. Isolated VICs exhibited an activated myofibroblast phenotype, expressing THY-1, vimentin, collagen and -smooth muscle actin (SMA) (n=9). Myofibroblasts expressed KCa3.1 mRNA and protein and demonstrated functional plasma membrane channels. TGF{beta}1 stimulation increased KCa3.1, SMA and collagen type I mRNA expression, while KCa3.1 blockade with senicapoc (100 nM) significantly attenuated TGF{beta}1-induced SMA expression, stress fibre formation and collagen gel contraction. Senicapoc had no effect on myofibroblast proliferation or migration. ConclusionsWe show for the first time that functional KCa3.1 channels are expressed in human AS tissue and AV myofibroblasts, where they regulate myofibroblast contraction, -SMA expression, and differentiation, promoting pro-fibrotic activity. These responses are attenuated by the selective KCa3.1 inhibitor senicapoc. Given its established safety in phase 3 clinical trials, KCa3.1 inhibition represents a promising and readily translatable anti-fibrotic therapeutic strategy for AS.

The liver and heart are tightly interconnected organs, and liver disease is frequently accompanied by cardiovascular dysfunction, including heart failure1-5. Despite this clinical association, the mechanisms by which liver-derived endocrine signals influence cardiac gene programs and disease susceptibility remain poorly defined. Inter-organ endocrine communication is increasingly recognized as a key regulator of systemic physiology, including cardiac function6-8, but a comprehensive understanding of liver-heart communication is lacking. Here we use an unbiased, population-based systems genetics approach in a genetically diverse mouse cohort to identify liver-derived secreted factors associated with cardiac transcriptomic variation. This analysis reveals hepatocyte growth factor activator (HGFAC) as a candidate mediator of inter-organ communication. Cross-tissue analysis of human genetic and transcriptomic datasets further suggests a conserved relationship between hepatic HGFAC expression and cardiac gene programs. These observations implicate a previously unrecognized liver-heart axis that appears to contribute to heart failure pathophysiology across species.

Collateral arteries are natural bypasses that can reroute blood flow around arterial blockages, limiting tissue injury during stroke and coronary artery disease. Despite their clinical effectiveness, therapeutic strategies to stimulate collateral artery growth remain unavailable due to our limited understanding of their developmental mechanisms. Remarkably, guinea pigs display exceptionally dense collateral artery networks across various organs, resulting in complete resistance to ischemic damage in the brain and heart. In this study, we compared single-cell RNA sequencing (scRNA-seq) from guinea pig and mouse tissues to identify endothelial cell (EC) gene expression patterns associated with extensive collateral artery development. We then developed an in vivo Perturb-seq platform in mice to test whether genes differentially expressed in guinea pigs influence artery EC specification. This pipeline identified artery repressors that were downregulated in guinea pigs and increased pial collateral abundance when inhibited in mice. Downstream analysis suggests that artery repressors, including WNT and hypoxia response genes, function in two capillary EC subsets--Esm1+ pre-artery and Apln+ angiogenic tip cells. Reduced activity of these repressors allows more ECs to acquire arterial identity, potentiating collateral artery formation. Collectively, our study establishes a strategy for discovering the genes underlying species-specific traits, suggests that guinea pigs have collaterals due to decreased activity of artery inhibitor pathways and hypoxia responses, and identifies novel targets for stimulating collateral artery formation (Graphical abstract). O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=174 SRC="FIGDIR/small/721711v2_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@1d6f264org.highwire.dtl.DTLVardef@c3ad35org.highwire.dtl.DTLVardef@a0af7dorg.highwire.dtl.DTLVardef@1614c61_HPS_FORMAT_FIGEXP M_FIG C_FIG

The heart maintains systemic perfusion through the coordinated function of its four chambers: the left and right atria and ventricles. Each chamber has distinct structural, functional, and molecular properties tailored to its role in circulation, which may result in chamber-specific differences in myofilament structure and regulation between atria and ventricles. To test this hypothesis, we employed muscle mechanics and X-ray diffraction to investigate functional and structural differences in porcine left atrial (LA) and left ventricular (LV) tissue. Here, we report the first X-ray diffraction study of atrial tissue, demonstrating that under resting conditions, myosin filaments in LA adopted a more ON-like, structurally distinct configuration compared with those in LV. Under contracting conditions, LV generated greater force and exhibited higher sinusoidal stiffness than LA across multiple calcium concentrations. LA showed faster kTR than in LV, with no calcium-dependence, in contrast to the calcium-dependence of kTR seen in LV. Structurally, the distinct myosin head configuration seen in the relaxed LA persisted during contraction. Furthermore, using the troponin inhibitor MYK-7660 to inhibit active contraction, we showed that, unlike LV, LA showed no direct calcium-dependent thick filament activation, reconciling discrepancies between fast rat and slow porcine ventricular myocardium regarding calciums role in thick filament regulation. Altogether, our study reveals that LA myosin filaments adopt a molecular architecture and regulatory mechanism distinct from their LV counterparts, suggesting that myosin filament structure and regulation have evolved differently to meet the unique functional demands of each cardiac chamber. Moreover, atrial disease is often associated with cardiomyopathy-related genetic variants, highlighting the atrial myocardium as an important therapeutic target and understanding atrial-specific regulatory mechanisms provides new insights into therapeutic strategies for atrial diseases.