Redfield, M M

Introduction: Endothelial cell (EC) dysfunction, driven by comorbidities of heart failure with preserved ejection fraction (HFpEF), has emerged as a potential contributor to disease progression, yet the EC specific molecular mediators in HFpEF remain poorly defined. Purpose: To identify EC-specific molecular mediators that are involved in HFpEF and determine their functional roles in disease pathogenesis. Hypothesis: Based on omics analysis of a murine HFpEF model, we hypothesized that EC plasminogen activator inhibitor-1 (PAI-1) is a key mediator of HFpEF pathogenesis. Methods: Male RiboTagEC (Cdh5CreERT2+/Rpl22HA/+) mice were used in a HFpEF model induced by hypertensive/metabolic stresses (60% calories from lard and L-NAME 0.5 g/L in water) or administrated with normal water and diet as controls. Hearts and skeletal muscle were collected for both bulk RNA sequencing (Bulk-seq) and EC-specific translatome analysis using translating ribosome affinity purification assay followed by RNA-sequencing (TRAP-seq). The functional roles of EC PAI-1 were tested using male tamoxifen-inducible, endothelial specific PAI-1 knockout (Cdh5CreERT2+/PAI-1flox/flox, PAI-1iEC KO) and control mice (PAI-1flox/flox, PAI-1iEC+/+) subjected to HFpEF induction. Cardiac function was assessed by echocardiography, pressure–volume (PV) loop analysis, and treadmill exercise testing. Student’s t-test was used (p < 0.05). Results: Bulk-seq and EC-specific TRAP-seq identified PAI-1 as one of the most upregulated genes in both heart and skeletal muscle EC in HFpEF. Bulk-seq demonstrated a 2.5-fold change (FC, log 2 FC=1.35) increases in the heart and 12.2-fold increases (log 2 FC = 3.61) in the skeletal muscle. TRAP-seq showed a 1.75-fold change (log 2 FC=0.81) increases in the heart and 4.76-fold increases (log 2 FC = 2.25) in the skeletal muscle. These consistent findings led us to investigate the functional role of EC PAI-1 in the pathogenesis of HFpEF. With similar body weight (Control: 40±4 g, n=10; KO: 38±6 g, n=11; p=0.319) and ejection fraction (Control: 54±6 %, n=10; KO: 54±5 %, n=12; p=0.686), we found that PAI-1iEC KO mice exhibited improved diastolic function after 10 weeks of HFpEF induction. Specifically, echocardiography demonstrated a significant reduction in E/e′ in KO mice (Control: 27±4, n=10; KO: 24±3, n=12; p=0.018). PV analysis confirmed this improvement with lower end-diastolic pressure (Control: 19±2 mmHg, n=8; KO: 13±5 mmHg, n=10; p=0.009), reduced Tau (Control: 9.7±1.2 ms, n=8; KO: 8.6±1.0 ms, n=10; p=0.047), and a reduced EDPVR constant β (Control: 0.20±0.05, n=6; KO: 0.10±0.03, n=6; p=0.017). KO mice also exhibited improved treadmill running distance (Control: 179±35 m, n=10; KO: 214±40 m, n=12; p=0.043). Conclusion: Endothelial PAI-1 contributes to diastolic dysfunction and reduced exercise capacity in HFpEF. These findings highlight endothelial PAI-1 as a potential therapeutic target for HFpEF. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Abstract Background Common genetic variation has been linked to an increased risk of developing dilated cardiomyopathy (DCM) in case-control studies. However, the phenotypic profile and biological mechanisms by which genetic background may predispose individuals to DCM and outcomes in the general population remain unclear. Aim The primary objectives of this study were twofold: (1) to validate a DCM polygenic score (PRS-1) based on a prior meta-analysis of case–control genetic association studies [Tadros R et al. Nat Genet (2021)]; and (2) To apply this PRS, along with two recently developed PRSs for DCM [PRS-2 from Zheng SL et al. Nat Genet (2024) and PRS-3 from Jurgens SJ et al. Nat Genet (2024)] to a general population that underwent comprehensive longitudinal phenotypic assessments and had long-term outcomes available. Methods While the PRS-1 was derived from only 13 SNPs, PRS-2 and PRS-3 were generated from 709,534 and 1,072,247 SNPs, respectively with significant overlap between them. These DCM-PRSs were applied to an unselected community-based cohort (n=1897) aged &gt;45 years, who underwent a physical examination, echocardiogram, and blood sample at baseline. Subsequent clinical outcomes were collected over a median 16 year follow-up (IQR: 15-17). Results No significant differences between the quartiles were present in terms of age, sex (48% male), and cardiovascular risk factors (CV-RF) (such as hypertension, diabetes, and coronary artery disease). However, linear regression models demonstrated a significant correlation between all DCM-PRSs and left ventricular (LV) parameters, including LV ejection fraction, LV end-systolic diameter, and LV end-diastolic diameter (Table). Multivariable regression analysis confirmed that these correlations were independent of age, sex, CV-RF, and population stratification (adjusted for the first 10 principal components [PCs]). During follow-up, 47 individuals developed DCM. A logistic regression analysis, using a 3:1 matched cohort of non-DCM vs. DCM individuals based on age and sex and adjusted for the same 10 PCs, found a significant correlation between DCM development and both PRS-1 [OR=2.27 (1.06–4.85), p=0.03] and PRS-3 [OR=2.63 (1.20–5.75), p=0.02], while PRS-2 did not show a significant association [OR=1.85 (0.84–4.06), p=0.12]. No association was found between the DCM-PRSs and heart failure (HF) biomarkers (aldosterone, natriuretic peptides, ST2, Galectin-3) or HF outcomes (all-cause mortality/HF hospitalization). Conclusion PRS-1 for DCM despite being derived from only 13 risk alleles, performs at least as well as the newer and more extensive PRSs, in its correlation with LV function, dimensions, and DCM development (except for PRS-2) in a general population. The absence of correlation between these DCM-PRSs and the renin-angiotensin-aldosterone system or natriuretic peptides suggests that genetic background influences LV traits through mechanisms independent of these biological pathways.