Introduction Anthracyclines, including doxorubicin (DOX), are highly effective chemotherapeutic agents, but their clinical use is hampered by late-onset cardiotoxicity, driven by poorly understood molecular mechanisms. Recently, metabolic impairments have been identified as a central feature of DOX-induced cardiotoxicity. Protein O-GlcNAcylation is a glucose-derived post-translational modification produced via the hexosamine biosynthetic pathway that couples nutrient availability to adaptive stress signalling during heart failure progression. Objective Here, we investigated whether protein O-GlcNAcylation is modified by DOX and could contribute to DOX-induced cardiotoxicity (DIC). Method C57BL/6N mice received DOX (4mg/kg) via 6 intraperitoneal injections over 2 weeks (cumulative dose 24mg/kg). Cardiac function was evaluated at baseline and 6 weeks after the first injection. In vitro, adult rat ventricular myocytes (ARVMs) were treated with DOX along with O-GlcNAc inhibitors (DON and AMPK agonists) and inducer (Thiamet-G) to modulate the O-GlcNAcylation pathway. Modulation of protein O-GlcNAcylation and of its regulatory enzymes (GFAT, OGT, and OGA), as well as AMPK activation were evaluated by western blot. Apoptosis was evaluated by examining the caspase-3 cleavage. Results Echocardiography revealed systolic dysfunction and cardiac atrophy 6 weeks after treatment, associated with increased cardiac protein O-GlcNAcylation. In ARVMs, DOX treatment promoted apoptosis and induced a dose- and time-dependent enhancement of protein O-GlcNAcylation, accompanied by reduced levels of OGA, the sole enzyme responsible for removing O-GlcNAc modifications, and by a decrease in AMPK signalling (reduced phosphoAMPK/AMPK ratio), known to negatively regulate O-GlcNAcylation. Pharmacological inhibition of O-GlcNAcylation (using DON or the AMPK agonist 991) attenuated DOX-induced apoptosis, while its stimulation (with Thiamet-G) promoted ARVM apoptosis. Conclusion Our findings implicate O-GlcNAcylation in DIC and highlight AMPK activation as a promising therapeutic avenue.

Abstract 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.

Abstract Platelets are increasingly recognized as active regulators of inflammation beyond their canonical hemostatic functions. Although platelets rapidly accumulate in the injured myocardium after myocardial infarction (MI), the mechanisms by which they coordinate the inflammatory response remain poorly understood. Glycoprotein A repetitions predominant (GARP) is a membrane receptor that presents latent transforming growth factor-β1 (TGF-β1) on activated platelets and supports its activation. Given the central role of TGF-β1 in inflammation and tissue repair, we hypothesized that platelet GARP-dependent activation of TGF-β1 regulates inflammatory resolution and repair after MI. Using mice with megakaryocyte-and platelet-specific Garp deletion, we demonstrate that loss of platelet GARP selectively impaired generation of bioactive TGF-β1 without altering platelet reactivity. Following permanent coronary artery ligation, platelet-specific Garp deficiency markedly increased mortality from ventricular rupture and exacerbated adverse left ventricular remodeling, independent of initial infarct size. Transcriptomic and histological analyses revealed heightened endothelial cell activation, increased leukocyte recruitment, delayed inflammatory resolution, and defective extracellular matrix deposition in the absence of platelet GARP. Mechanistically, platelet GARP-dependent TGF-β1 signaling restrained endothelial activation after MI. Together, these findings identify platelet GARP-mediated activation of TGF-β1 as a critical platelet-intrinsic counter-regulatory checkpoint that limits endothelial-driven inflammation and promotes infarct stabilization. Our study reveals an unexpected protective immunoregulatory function of platelets in cardiac repair after ischemic injury.

Introduction Cardiovascular diseases are the leading cause of mortality in patients with type 2 diabetes. In addition to vascular complications, these patients are at risk of developing diabetic cardiomyopathy (DCM), a cardiac dysfunction that can lead to heart failure. DCM is notably characterized by a metabolic shift in which the heart relies excessively on fatty acids at the expense of glucose. Existing literature suggests that protein acetylation may play a key role in this metabolic reprogramming. Our group previously showed that metabolic overload increases cardiomyocyte protein acetylation, which inhibits insulin-stimulated glucose uptake. However, the temporal relationship between protein acetylation, cardiac insulin resistance (IR), and cardiac dysfunction during DCM development remains unclear. Objective To determine the role of protein acetylation in the development of cardiac IR and dysfunction during DCM, and to investigate whether similar mechanisms occur in skeletal muscle. Method C57Bl/6N mice were fed a high-fat diet (HFD) for 1 or 2 months. Cardiac function was assessed by echocardiography. Insulin signaling and protein acetylation were analyzed in vivo and ex vivo in the heart and skeletal muscles (soleus and gastrocnemius). Glucose uptake was measured in cardiomyocytes by following the detritiation rate of [2-3H]-glucose. Results After 1 month of HFD, protein acetylation was increased in the heart and soleus but remained unchanged in the gastrocnemius, while insulin signaling was not altered in any of the tissues. After 2 months of HFD, insulin signaling was reduced in all three tissues and glucose uptake, assessed in cardiomyocytes derived from HFD mice, was also significantly reduced. Systolic cardiac function showed a gradual decline, with a trend toward reduction already apparent after 1 month of HFD. Conclusion Increased protein acetylation under HFD precedes the development of cardiac IR and dysfunction.

Among potential molecular mechanisms supporting cardiovascular homeostasis, miRNAs (miRs) represent interesting candidates. We recently highlighted that miR-199a controls the Nitric oxide synthase/nitric oxide (NOS/NO) pathway in the endothelium and showed that both mature strands of miR-199a are overexpressed in heart and vessels from a mouse model of hypertension. Here we investigated the fate of miR-199a in heart and vessels from mice developing physiological or pathological cardiac hypertrophy. Our working hypothesis is that alterations in cell phenotypes driven by changes in miR-199a abundance account for cardiac and/or vascular adaptation to increased workload in patho-physiological contexts. C57BL/6J mice were given access to voluntary dynamic wheel training during 22 weeks or underwent transverse aortic constriction (TAC) surgery. As a result, those mice respectively developed physiological and pathological cardiac hypertrophy. An opposite modulation of miR-199a-3p and miR-199a-5p expression was observed in vessels and heart from running vs TAC mice which correlated with opposite regulation of Retinobastoma1 (RB1) in cardiac tissue. We show that miR-199a-3p upregulation, by indirectly modulating CCAAT/enhancer binding protein (C/EBP)β, promotes cardiomyocyte hypertrophy in the pathological settings, while its repression by exercise drives metabolic adaptations associated with physiological remodeling. Interestingly, miR-199a-5p repression also directly target Sirtuin 1 (Sirt-1) and Peroxisome proliferator-activated receptor coactivator (PGC1)α Taken together, our findings indicate that both mature arms of miR-199a act in tandem to drive morphologic and metabolic adaptations encountered in physiological and pathological cardiac hypertrophy.

Sirtuin 3 (SIRT3) is a nicotinamide adenine dinucleotide (NAD)-dependent mitochondrial deacetylase that regulates protein acetylation and maintains mitochondrial homeostasis in nucleated cells. By deacetylating cyclophilin D (CypD), SIRT3 limits mitochondrial permeability transition pore (mPTP) opening and protects against mitochondrial dysfunction. Although SIRT3 is present in murine and human platelets, its contribution to platelet mitochondrial regulation and procoagulant platelet formation remains unknown. This study investigated whether platelet SIRT3 modulates CypD-dependent procoagulant platelet formation. Platelets obtained from platelet-specific Sirt3 knockout mice (Sirt3plt-/-) and littermate controls (Sirt3plt+/+) were analyzed under resting conditions and after activation with CRP-XL and thrombin. Flow cytometry was used to analyze platelet (activation) markers and procoagulant platelet formation, and mitochondrial respiration was assessed using a Seahorse extracellular flux analyzer. Platelets lacking SIRT3 showed no alterations in basal or agonist-stimulated mitochondrial respiration. Likewise, platelet Sirt3 deletion did not affect the generation of procoagulant platelets in response to strong dual agonist stimulation. These findings indicate that, despite its role in regulating mPTP opening in nucleated cells, platelet SIRT3 is not required for procoagulant platelet formation, suggesting that platelets rely on distinct mechanisms for mPTP regulation.

Aims Recent clinical studies have reported that myo-inositol is consistently elevated in plasma of patients with heart failure (HF), yet its role in cardiac dysfunction remains poorly understood. Myo-inositol is specifically transported into cells by the sodium-myo-inositol co-transporter-1 (SMIT1), a member of the sodium-glucose co-transporter (SGLT) family expressed in the heart. While myo-inositol is essential for phosphoinositide signalling, osmoregulation, and metabolic homeostasis, dysregulation of SMIT1-mediated myo-inositol transport may contribute to key pathological mechanisms in HF. This study aims to elucidate the role of SMIT1 in the failing heart, especially during left ventricular remodelling that precedes it. Methods and results We used a mouse model of pressure overload induced by transverse aortic constriction in wild-type (WT) mice and mice lacking SMIT1 (Smit1(-/-)), and primary cultured cardiomyocytes. By combining molecular, structural and functional studies, RNA-sequencing, and calcium measurements, we demonstrate the contribution of myo-inositol and SMIT1 to pathological hypertrophy and the progression towards HF. We found that in comparison to WT controls, Smit1(-/-) mice were protected against aortic banding induced systolic dysfunction, cardiac fibrosis and hypertrophy. This hypertrophic response was driven by SMIT1 expression in cardiomyocytes, where it favours intracellular myo-inositol and Na+ entry, leading to inositol 1,4,5-trisphosphate (IP3)- and Ca2+-dependent pro-hypertrophic signalling. Following haemodynamic stress, deletion of SMIT1 significantly altered IP3/calcium effectors, including Carabin, which modulates cardiac hypertrophy through inhibition of the calcineurin/nuclear factor of activated T-cell and Ras/ERK1/2 pathways. Conclusion This work provides important insights into the role of myo-inositol and SMIT1 in cardiomyocytes. We demonstrate that SMIT1 is a key driver of pathological hypertrophy by inducing an IP3/Ca2+-dependent pro-hypertrophic transcriptional reprogramming in cardiomyocytes. These findings identify SMIT1 as a promising therapeutic target for preventing or treating pathological cardiac hypertrophy and HF.

Introduction Platelet GARP:latent TGF-β1 is a key regulator of post-myocardial infarction (MI) repair. It balances early inflammation by modulating endothelial activation while promoting the formation of a functional extracellular matrix. Although COX-1 and P2Y12 inhibitors are clinical standards, their influence on this immunomodulatory axis remains unknown. Objective We aimed to evaluate how aspirin (COX-1 inhibitor) and cangrelor (P2Y12 antagonist) modulate platelet GARP:latent TGF-β1 expression and to correlate these changes with conventional activation markers to determine how standard therapeutic interventions modulate this emerging immunomodulatory axis. Method Platelets were isolated from the whole blood of healthy volunteers and were stimulated with thrombin to induce activation. Platelets were then incubated with aspirin or cangrelor. Surface expression of GARP and LAP (latent-associated peptide/TGF-β1), alongside activation markers CD62P and activated GPIIb/IIIa(PAC-1 binding), was quantified by flow cytometry using a BD FACSCanto II. Data was processed with FlowJo v10.10, and statistical analyses were performed using GraphPad Prism 10. Results Thrombin stimulation in the proposed concentration induced near-maximal surface expression of CD62P and PAC-1. Thrombin also induces the externalization of the GARP:LAP complex, but in a lower relative amplitude.Treatment with either aspirin or cangrelor resulted in a significant reduction in the surface expression of all four targets compared to their respective activated controls (P<0.05).No dose-dependent differences were observed in the two selected concentrations of aspirin and cangrelor, suggesting that maximal inhibition was achieved at the lower concentrations tested.Notably, the inhibitory patterns for GARP and LAP closely mirrored those of the classical activation markers CD62P and PAC-1. Conclusion Our study demonstrates that conventional antiplatelet therapies significantly modulate the GARP:latent TGF-β1 expression on platelet, which closely mirrors the kinetics of classical activation markers.

AIMS:Structural valve degeneration (SVD) is the leading cause of late bioprosthetic valve failure. Lipoprotein(a) [Lp(a)] contributes to native aortic valve calcification, but its role in SVD is unclear. We investigated whether elevated Lp(a) is associated with SVD after bioprosthetic aortic valve replacement (AVR) and whether this differs between stenotic and regurgitant phenotypes. METHODS AND RESULTS:We studied 174 bioprosthetic AVR patients with available Lp(a) levels over a median echocardiographic follow-up of 7.3 years (1372 studies). SVD was defined by VARC-3 criteria, and associations were analysed with Fine-Gray competing risk models. Lp(a) was evaluated categorically (≤ or > 125 nmol/L) and continuously using spline modelling. During follow-up, 40 patients developed SVD (22 stenotic, 9 mixed, and 9 regurgitant). The 15-year cumulative incidence was 51% with a median onset at 14.8 years. Elevated Lp(a) was associated with a higher risk of overall SVD (62% vs. 47%; SHR 2.06, 95% CI 1.09-3.91; P = 0.026) and specifically with stenotic/mixed phenotypes (SHR 2.57, 95% CI 1.26-5.23; P = 0.009). No association was observed with regurgitant phenotypes (SHR 0.85, 95% CI 0.19-3.92; P = 0.84). After multivariable adjustment, elevated Lp(a) remained an independent predictor of stenotic/mixed SVD (adjusted SHR 3.00, 95% CI 1.48-6.07; P = 0.002). Spline modelling showed a linear dose-response, with each 25 nmol/L increase in Lp(a) conferring 13% higher risk. CONCLUSION:Elevated Lp(a) is independently associated with long-term risk of stenotic/mixed SVD. These findings highlight Lp(a) as a promising biomarker of prosthetic valve vulnerability and support investigation of emerging Lp(a)-lowering therapies to improve valve durability.

Introduction Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous syndrome characterized by distinct phenotypes driven by comorbidities. The SAUNA model (salt, aldosterone, unilateral nephrectomy) recapitulates key features of hypertensive HFpEF and is increasingly used in preclinical studies. However, accumulating evidence indicates that genetic differences between commonly used C57BL/6J and C57BL/6N mouse substrains influence cardiovascular and inflammatory responses, potentially affecting model reproducibility. As HFpEF pathophysiology involves both cardiac remodelling and systemic inflammation, it is essential to determine how substrain-specific genetics impact the SAUNA model. Objective To investigate the influence of C57BL/6 substrain genetics on cardiac remodelling, inflammatory responses, and endothelial activation induced by the SAUNA protocol. Method Male C57BL/6J and C57BL/6N mice underwent unilateral nephrectomy, continuous d-aldosterone infusion (0.30μg/day for 4 weeks), and received 1% NaCl in drinking water. Cardiac structure and function were assessed by echocardiography and pressure-volume analysis. Cardiac hypertrophy and fibrosis, systemic inflammation, and endothelial activation were evaluated using qPCR, immunohistochemistry and plasma biomarkers. Results The SAUNA protocol induced a reproducible HFpEF-like phenotype in both substrains, characterized by cardiac hypertrophy, increased E/e’, preserved systolic function, and impaired diastolic compliance. Notably, inflammatory responses differed between substrains. C57BL/6J mice developed a robust systemic inflammatory response, with elevated circulating TNFα, IL-6 and IL-17a levels, associated with a significant macrophage infiltration in the left ventricle. In contrast, C57BL/6N mice showed minimal systemic inflammation and no detectable macrophage infiltration in cardiac tissue. Conclusion The SAUNA protocol reliably induces key cardiac features of HFpEF in both C57BL/6 substrains, only C57BL/6J mice develop a pronounced systemic and cardiac inflammatory phenotype. Conversely, C57BL/6N mice exhibit HFpEF-like cardiac dysfunction in a relative absence of inflammation. These findings highlight substrain selection as a critical determinant when modelling inflammatory mechanisms in HFpEF and have important implications for experimental reproducibility and translational relevance.

Introduction An elevation of O-GlcNAcylation, a post-translational modification derived from glucose metabolism, has been observed and involved in the development of type 2 diabetes and diabetic cardiomyopathy (DCM). Moreover, a sexual dimorphism has been observed with diabetic women exhibiting a higher level of O-GlcNAcylation levels and higher risk of cardiovascular complications. Objective This project aims to characterize sex-specific differences in the development of type 2 diabetes and DCM in mice, with a focus on cardiac O-GlcNAcylation. The impact of female hormones on this phenotype will be further evaluated using ovariectomized animals. Method Male and female C57BL/6N mice were fed either a standard diet (SD) or a Western diet (WD) rich in fats and sugars for four months. Body weight, glucose tolerance, fasting glycemia, and cardiac function were monitored over time, while cardiac O-GlcNAcylation levels were analyzed by Western blot after euthanasia at different time points. Additional cohorts of female mice, which underwent ovariectomy (OV) or SHAM surgery, were similarly submitted to SD or WD and characterized using the same parameters. Results WD induces a progressive obesity in both sexes, though this occurs later in females. Males develop more pronounced glucose intolerance and earlier hyperglycemia with noticeable cardiac systolic dysfunction, whereas female mice are protected from cardiac dysfunction. WD increases cardiac protein O-GlcNAcylation in both sexes; however, basal levels were higher in females. WD also induces progressive obesity in both SHAM and OV female mice, while no difference of glucose intolerance was observed. Interestingly, cardiac protein O-GlcNAcylation levels are higher in OV-WD mice. Cardiac function evaluation in these OV cohort is under investigation. Conclusion In conclusion, female mice display resistance to WD-induced DCM, which may be partly explained by sex-dependent differences in cardiac O-GlcNAcylation. Even though OV-WD mice do not appear to be more obese or diabetic than WD females in control conditions, they have higher O-GlcNAcylation level, hypothesizing a potential more severe cardiac dysfunction.

Background In pro-inflammatory conditions, such as atherosclerosis, circulating monocytes may express tissue factor (TF), increasing thromboembolic risk. Regular physical activity (PA) has been shown to modulate hemostasis by reducing fibrinogen concentration and platelet activation, though its effects on coagulation are limited. Objectives We aim to evaluate the procoagulant and proinflammatory state in asymptomatic patients with atherosclerotic carotid stenosis, compared to healthy subjects and to assess the impact of a 6-month PA intervention. Methods This study included patients with asymptomatic carotid stenosis and healthy subjects. Patients were randomized into a PA group (6-month individualized PA intervention), and a control group. Blood analyses were performed to assess monocyte phenotype and TF expression by flow cytometry, and coagulation parameters using rotative thromboelastometry. Results The expression of TF on the surface of circulating monocytes was significantly higher in patients than in healthy subjects (61.9 ± 11.7 % vs 33.7 ± 6.3 %, p < 0.0001), mainly explained by a higher expression on classical monocytes (77.7 ± 9.5 vs 58.3 ± 15.8 %, p < 0.001). Clotting times were lower in patients than in healthy subjects in basal (407.8 77.7 ± 144.6 s vs 615.5 ± 123.4 s p < 0.0001) and proinflammatory (222.4 ± 48.2 s vs 307.8 ± 82.4 s p = 0.003) conditions. A 6-month PA intervention did not induce any modulation of the monocyte phenotype or coagulation parameters of patients with atherosclerosis. Conclusion Asymptomatic patients with carotid atherosclerosis have a higher proinflammatory and procoagulant profile, suggesting a higher thromboembolic risk. However, home-based PA intervention did not improve their profiles.

Background: Platelets play a central role in hemostatic and inflammatory responses during septic shock, with lipids being essential for their function. However, the specific lipidomic alterations occurring in platelets during septic shock remain poorly understood. Objectives: This study aimed to characterize platelet lipidomic changes in septic shock and investigate their associations with disease severity. Methods: In this matched case-control study, platelets were isolated from 49 septic shock patients and 47 nonseptic controls (matched for age, gender, and comorbidities). Lipidomic profiling was performed using untargeted lipidomics to identify significant alterations in the platelet lipidome. Associations among lipid changes, clinical data, and plasma biomarkers of coagulopathy and inflammation were explored. Results: More than 60% of the annotated platelet lipids were significantly altered in septic shock. Cholesteryl esters, sphingomyelins, lysophosphatidylcholines, and ether-lipids were significantly reduced, while ceramide levels increased. Fatty acyl chain remodeling displayed distinct patterns, with polyunsaturated fatty acids increasing in triacylglycerols and decreasing in phospholipids. Lipid alterations were strongly associated with thrombocytopenia, and lysophosphatidylcholine levels inversely correlated with disease severity, as indicated by the Sequential Organ Failure Assessment score. Conclusions: Septic shock induces significant disruptions in the platelet lipidome, with the extent of these alterations correlating with sepsis-associated thrombocytopenia severity. The observed changes affect multiple lipid classes, surpassing those reported under physiological conditions or in other diseases. These findings highlight the impact of sepsis-driven dysregulated inflammation and coagulopathy on platelet lipid composition, providing new insights into sepsis pathophysiology.

Biodegradable intravascular stents offer a promising alternative to permanent stents for treating atherosclerosis-related artery narrowing by potentially avoiding long-term complications. Identifying materials that degrade harmlessly and uniformly at a suitable rate is crucial. This study evaluated an advanced zinc alloy (Zn-Ag-Cu-Mn-Zr) alongside pure iron and pure zinc, using a simplified stent model of metallic wires implanted in the rat aorta. Assessments were made at 7, 24, and 84 days post-implantation using X-ray microfocus computed tomography (microCT) and contrast-enhanced microCT (CECT). For CECT, a contrast agent was chosen to provide optimal soft tissue contrast and minimal interaction with the wires. This combination of imaging techniques allowed us to evaluate degradation behavior, compare volume loss in various locations (outside the arterial lumen, inside the lumen, and encapsulated by neointima), compute degradation rates, and evaluate neointima tissue formation. Results showed that zinc and its alloy degrade less uniformly than iron, which demonstrates uniform surface degradation. The zinc alloy had a higher initial volume loss than the other materials but showed little increase over time. Neointima formation was similar for zinc and the zinc alloy, while iron provoked less tissue formation than both zinc and the reference cobalt-chromium alloy. Additionally, unlike cobalt-chromium and zinc, iron wires did not achieve consistent tissue encapsulation along their entire length, which may impair their performance. Mild inflammation was noted around zinc-based implants. Combining microCT and CECT provided 3D information on degradation uniformity, degradation products, and neointima morphometrics, highlighting the power of these imaging techniques to evaluate implant materials in a highly accurate way compared to previous 2D methods. Statement of Significance Biodegradable intravascular stents offer a promising solution to long-term complications associated with permanent stents by gradually dissolving in the body. To evaluate a novel zinc alloy (Zn-Ag-Cu-Mn-Zr) with improved mechanical properties, microstructure, and biocompatibility, we compared it to pure iron and zinc. We used advanced 3D imaging techniques, i.e., microCT and contrast-enhanced microCT, to assess the degradation behavior and the tissue response in a rat aorta model. The zinc alloy demonstrated promising properties despite less uniform degradation and mild inflammation compared to iron. Our findings highlight the superiority of 3D imaging over previously used 2D techniques in evaluating stent materials, offering critical insights into degradation processes and biocompatibility. These highly accurate measurements provide crucial information for developing improved biodegradable implants.

Abstract: This study uncovers the pivotal role of acetyl-CoA carboxylase 1 (ACC1) in regulating platelet lipid composition, bioenergetics, activation, and thrombus formation, as demonstrated using a targeted glycoprotein Ibα (GPIbα)-Cre+/− mouse model. By comparing platelet-specific ACC1 knockout mice (GPIbα-Cre+/− × ACC1flx/flx) with both GPIbα-Cre+/− and ACC1flx/flx control groups, we showed that ACC1 deficiency profoundly reshaped the platelet phospholipidome. Specifically, ACC1 deletion led to decreased levels of arachidonic acid–containing phosphatidylethanolamine plasmalogens, thereby limiting thromboxane A2 synthesis, dense granule secretion, and platelet activation upon agonist stimulation. Bioenergetic analysis of ACC1-deficient platelets revealed reduced glycolytic activity, potentially worsening their activation defects. Notably, ACC1 deficiency also enhanced the mitochondrial reserve respiratory capacity, without altering basal respiration or adenosine triphosphate turnover. This increased reserve respiratory capacity correlated with reduced phosphatidylserine exposure, suggesting lower procoagulant activity. Importantly, we showed that ACC1 deficiency impaired thrombus formation without compromising hemostasis. Together, these findings identified ACC1 as a critical regulator of platelet function and highlighted its potential as a target for innovative antithrombotic therapies.

Background: Thrombocytopenia is common in pediatric patients with cirrhosis, but the extent and relevance of functional platelet defects remain unclear. Objectives: This proof-of-principle study aimed to characterize platelet properties in cirrhotic children before living-donor liver transplantation using state-of-the-art platelet-based assays, hypothesizing that primary hemostasis in this group is well preserved. Methods: From January 2022 to July 2023, pediatric cirrhotic patients were prospectively enrolled 1 day before liver transplantation. An age-matched control group was included. Platelet functionality was assessed using flow cytometry and microfluidic assays, along with plasma proteins including von Willebrand factor (VWF), a disintegrin and metalloproteinase with a thrombospondin type 13, and soluble glycoprotein VI. A subset of patients was also re-evaluated 3 months after transplant. Results: Twenty-seven pediatric cirrhotic patients, primarily with cholestatic liver disease, and 15 controls were enrolled. Patients had pediatric end-stage liver disease scores from-10 to 44. Flow cytometry revealed subtle platelet activation in the absence of agonists and reduced activation with high agonist concentrations. Micro-fluidic assays revealed variations in platelet thrombus formation among the patients, identifying 2 distinct subgroups: 1 with severe liver disease and higher platelet counts, showing preserved primary hemostasis, and another with lower platelet count and moderate platelet thrombus impairment. High VWF levels likely compensated for reduced platelet activation under high shear. Conclusion: Two subgroups with differences in platelet thrombus formation under flow were identified pretransplantation, likely depending on severity of liver disease, platelet count, and VWF levels. Whether the need for platelet intervention is different between these subgroups requires further clinical investigation.

BACKGROUND Myocardial hypertrophy caused by chronic pressure overload eventually leads to heart failure. Increased protein synthesis and sarcomere reorganization are crucial elements of cardiac remodeling under such conditions. The muscle-specific nascent polypeptide-associated complex alpha isoform (skNAC) is a protein essential for proper sarcomere organization during development. However, its role in hypertrophy and heart failure in adults remains unexplored. We investigated the function of skNAC in pressure overload-induced hypertrophy and heart failure. METHODS skNAC expression was assessed in neonatal rat ventricular cardiomyocytes (NRVMs) stimulated with phenylephrine, in human cardiac biopsies, and in mice subjected to transverse aortic constriction (TAC) or angiotensin II infusion. The impact of siRNA-mediated skNAC silencing was evaluated in NRVMs, while constitutive and inducible cardiomyocyte-specific skNAC knockout mouse models were generated to examine the long-term effects of skNAC deletion under both basal and TAC conditions. Immunofluorescence confocal microscopy and proximity ligation assay were used to assess skNAC localization and interactions, while electron microscopy was employed to analyze the consequences of skNAC deletion on cardiomyocyte ultrastructure. RESULTS skNAC expression was reduced in phenylephrine-treated NRVMs and in mice subjected to TAC or angiotensin II, due to decreased expression of the RNA-binding proteins Rbm24 and Rbm20, which regulate skNAC pre-mRNA splicing. Consistently, skNAC expression inversely correlated with cardiac hypertrophy and NT-proBNP levels in humans. Cardiomyocyte-specific skNAC deletion generated basal hypertrophy, severe systolic dysfunction, and premature death, which were further exacerbated by TAC surgery, leading to rapid dilated cardiomyopathy and lethality. skNAC strongly colocalized with ribosomes, and its deletion caused sarcomere disorganization and an autophagic response. Conversely, skNAC overexpression prevented phenylephrine-induced hypertrophy in NRVMs. CONCLUSIONS Our results demonstrate that skNAC is essential for preserving sarcomere integrity and cardiomyocyte homeostasis. Its downregulation drives pathological remodeling and heart failure, positioning skNAC as a promising therapeutic target. What is known? What new information does this article contribute? ### Competing Interest Statement The authors have declared no competing interest.