Platelet lipidomics and de novo lipogenesis: impact on health and disease.

PURPOSE OF REVIEW: Lipids play vital roles in platelet structure, signaling, and metabolism. In addition to capturing exogenous lipids, platelets possess the capacity for de novo lipogenesis, regulated by acetyl-coA carboxylase 1 (ACC1). This review aims to cover the critical roles of platelet de novo lipogenesis and lipidome in platelet production, function, and diseases. RECENT FINDINGS: Upon platelet activation, approximately 20% of the platelet lipidome undergoes significant modifications, primarily affecting arachidonic acid-containing species. Multiple studies emphasize the impact of de novo lipogenesis, with ACC1 as key player, on platelet functions. Mouse models suggest the importance of the AMPK-ACC1 axis in regulating platelet membrane arachidonic acid content, associated with TXA2 secretion, and thrombus formation. In human platelets, ACC1 inhibition leads to reduced platelet reactivity. Remodeling of the platelet lipidome, alongside with de novo lipogenesis, is also crucial for platelet biogenesis. Disruptions in the platelet lipidome are observed in various pathological conditions, including cardiovascular and inflammatory diseases, with associations between these alterations and shifts in platelet reactivity highlighted. SUMMARY: The platelet lipidome, partially regulated by ACC-driven de novo lipogenesis, is indispensable for platelet production and function. It is implicated in various pathological conditions involving platelets.

Left Atrial Glucose Metabolism Evaluation by 18F-FDG-PET in Persistent Atrial Fibrillation and in Sinus Rhythm.

The role of atrial metabolism alterations for initiation and atrial fibrillation (AF) persistence remains poorly understood. Therefore, we evaluated left atrial glucose metabolism by nicotinic acid derivative stimulated 18-fluorodeoxyglucose positron emission tomography in 36 patients with persistent AF undergoing catheter ablation before and 3 months after return to sinus rhythm and compared values against healthy controls. Under identical hemodynamics and metabolic conditions, and although left ventricular FDG uptake remained unchanged, patients in persistent AF presented significantly higher total left atrial and left atrial appendage uptake, which decreased significantly after return to sinus rhythm, despite improvement of passive and active atrial contractile function. These findings support a role of altered glucose metabolism and metabolic wasting underlying the pathophysiology of persistent AF.

Laboratory Testing for Endocrine Hypertension: Current and Future Perspectives.

BACKGROUND: Secondary hypertension (SH) is a form of high blood pressure caused by an identifiable underlying condition. Although, it accounts for a small fraction of the overall hypertensive population, detection and management of SH is of utmost importance, because SH phenotypes carry a high cardiovascular risk and can possibly be cured by timely treatment. CONTENT: This review focuses on the endocrine causes of SH, such as primary aldosteronism, Cushing syndrome, thyroid disease, pheochromocytoma and paraganglioma, acromegaly, and rare monogenic forms. It discusses current biomarkers, analytical methods, and diagnostic strategies, highlighting advantages and limitations of each approach. It also explores the emerging -omics technologies that can provide a comprehensive and multidimensional assessment of SH and its underlying mechanisms. SUMMARY: Endocrine SH is a heterogeneous and complex condition that requires proper screening and confirmatory tests to avoid diagnostic delays and improve patient outcomes. Careful biomarker interpretation is essential due to potential interferences, variability, and method-dependent differences. Liquid chromatography-tandem mass spectrometry is a superior method for measuring low-concentration hormones and metabolites involved in SH, but it requires expertise. Omics approaches have great potential to identify novel biomarkers, pathways, and targets for SH diagnosis and treatment, especially considering its multifactorial nature.

Carbohydrate antigen 125: a useful marker of congestion, fibrosis, and prognosis in heart failure with preserved ejection fraction.

AIMS: Heart failure (HF) with preserved ejection fraction (HFpEF) is a disease associated with high morbidity and mortality, for which it is difficult to identify patients with the poorest prognosis in routine clinical practice. Carbohydrate antigen 125 (CA 125) has been shown to be a potential marker of congestion and prognosis in HF. We sought to better characterize HFpEF patients with high CA 125 levels by using a multimodal approach. METHODS AND RESULTS: We prospectively enrolled 139 HFpEF patients (78 ± 8 years; 60% females) and 25 controls matched for age and sex (77 ± 5 years; 60% females). They underwent two-dimensional echocardiography, cardiac magnetic resonance with late gadolinium enhancement [including extracellular volume (ECV) measurement], and serum measurements of CA 125 level. The primary endpoint of the study was a composite of all-cause mortality or first HF hospitalization. The prognostic impact of CA 125 was determined using Cox proportional hazard models. Median CA 125 levels were significantly higher in HFpEF patients compared with controls [CA 125: 23.5 (14.5-44.7) vs. 14.6 (10.3-21.0) U/mL, P = 0.004]. CA 125 levels were positively correlated with a congestion marker [N-terminal pro-brain natriuretic peptide (NT-proBNP) levels, Pearson's r = 0.37, P < 0.001] and markers of cardiac fibrosis estimated by both ECV (Pearson's r = 0.26, P = 0.003) and fibroblast growth factor 23 levels (Pearson's r = 0.50, P < 0.001). Over a median follow-up of 49 (22-64) months, 97 HFpEF patients reached the composite endpoint. Even after adjustment for the Meta-Analysis Global Group in Chronic risk score, a CA 125 level ≥35 U/mL was still a significant predictor of the composite endpoint [hazard ratio (HR): 1.58 (1.04-2.41), P = 0.032] and more particularly of HF hospitalization [HR: 1.81 (1.13-2.92), P = 0.014]. In contrast, NT-proBNP levels were not an independent predictor. CONCLUSIONS: CA 125 levels were significantly higher in HFpEF patients compared with controls matched for age and sex and were associated with markers of congestion and cardiac fibrosis. CA 125 levels were a strong and independent predictor of HF hospitalization in HFpEF patients. These data suggest a potential value of CA 125 as a biomarker for staging and risk prediction in HFpEF.

Potential for recovery after extremely prolonged VV-ECMO support in well-selected severe COVID-19 patients: a retrospective cohort study.

BACKGROUND: VenoVenous ExtraCorporeal Membrane Oxygenation (VV-ECMO) has been widely used as supportive therapy for severe respiratory failure related to Acute Respiratory Distress Syndrome (ARDS) due to coronavirus 2019 (COVID-19). Only a few data describe the maximum time under VV-ECMO during which pulmonary recovery remains possible. The main objective of this study is to describe the outcomes of prolonged VV-ECMO in patients with COVID-19-related ARDS. METHODS: This retrospective study was conducted at a tertiary ECMO center in Brussels, Belgium, between March 2020 and April 2022. All adult patients with ARDS due to COVID-19 who were managed with ECMO therapy for more than 50 days as a bridge to recovery were included. RESULTS: Fourteen patients met the inclusion criteria. The mean duration of VV-ECMO was 87 ± 29 days. Ten (71%) patients were discharged alive from the hospital. The 90-day survival was 86%, and the one-year survival was 71%. The evolution of the patients was characterized by very impaired pulmonary compliance that started to improve slowly and progressively on day 53 (± 25) after the start of ECMO. Of note, four patients improved substantially after a second course of steroids. CONCLUSIONS: There is potential for recovery in patients with very severe ARDS due to COVID-19 supported by VV-ECMO for up to 151 days.

Fibroblasts and platelets: a face-to-face dialogue at the heart of cardiac fibrosis.

Myocardial fibrosis is a feature found in most cardiac diseases and a key element contributing to heart failure and its progression. It has therefore become a subject of particular interest in cardiac research. Mechanisms leading to pathological cardiac remodeling and heart failure are diverse, including effects on cardiac fibroblasts, the main players in cardiac extracellular matrix synthesis, but also on cardiomyocytes, immune cells, endothelial cells, and more recently, platelets. Although transforming growth factor-ß (TGF-ß) is a primary regulator of fibrosis development, the cellular and molecular mechanisms that trigger its activation after cardiac injury remain poorly understood. Different types of anti-TGF-ß drugs have been tested for the treatment of cardiac fibrosis and have been associated with side effects. Therefore, a better understanding of these mechanisms is of great clinical relevance and could allow us to identify new therapeutic targets. Interestingly, it has been shown that platelets infiltrate the myocardium at an early stage after cardiac injury, producing large amounts of cytokines and growth factors. These molecules can directly or indirectly regulate cells involved in the fibrotic response, including cardiac fibroblasts and immune cells. In particular, platelets are known to be a major source of TGF-ß1. In this review, we have provided an overview of the classical cellular effectors involved in the pathogenesis of cardiac fibrosis, focusing on the emergent role of platelets, while discussing opportunities for novel therapeutic interventions.

Cardiac structure, function, and coronary anatomy 10 years after isolated contemporary adjuvant radiotherapy in breast cancer patients with low cardiovascular baseline risk.

AIMS: The effects of isolated contemporary low-dose breast cancer (BC) radiotherapy (RT) on the heart remain poorly understood. This study aims to assess the long-term impacts of BC-RT on cardiac structure and function. METHODS AND RESULTS: Seventy-six women (62 ± 7 years) without history of prior heart disease, who had undergone RT for either first left (n = 36) or right (n = 40) BC, without additional medical oncology therapy apart from hormonal treatment 11 ± 1 years earlier, underwent transthoracic echocardiography, cardiac magnetic resonance imaging (CMR), computed tomography coronary angiography (CTCA), NT-proBNP, and a 6-min walk test (6MWT). They were compared with 54 age-matched healthy female controls. By CTCA, 68% of BC patients exhibited no or very mild coronary disease, while only 11% had moderate stenosis (50-69%) and 3% had significant stenosis (>70%). Despite slightly reduced regional echocardiographic midventricular strains, BC patients exhibited similar global left and right ventricular volumes, ejection fractions, and global strains by echocardiography and CMR as controls. Mitral E/e' ratios were slightly higher, and mitral deceleration times were slightly lower, but NT-proBNP was similar to controls. Also, 6MWT was normal. None had late gadolinium enhancement, and extracellular volume fraction was similar in BC (28 ± 3 vs. 29 ± 3, P = 0.15) and controls. No differences were observed relative to dose or side of RT. CONCLUSION: Aside from minor alterations of regional strains and diastolic parameters, women who received isolated RT for BC had low prevalence of coronary disease, normal global systolic function, NT-proBNP, and exercise capacity and showed no structural changes by CMR, refuting significant long-term cardiotoxicity in such low-risk patients.

Acute heart failure: mechanisms and pre-clinical models-a Scientific Statement of the ESC Working Group on Myocardial Function.

While chronic heart failure (CHF) treatment has considerably improved patient prognosis and survival, the therapeutic management of acute heart failure (AHF) has remained virtually unchanged in the last decades. This is partly due to the scarcity of pre-clinical models for the pathophysiological assessment and, consequently, the limited knowledge of molecular mechanisms involved in the different AHF phenotypes. This scientific statement outlines the different trajectories from acute to CHF originating from the interaction between aetiology, genetic and environmental factors, and comorbidities. Furthermore, we discuss the potential molecular targets capable of unveiling new therapeutic perspectives to improve the outcome of the acute phase and counteracting the evolution towards CHF.

Dual antiplatelet therapy is associated with high α-tubulin acetylation in circulating platelets from coronary artery disease patients.

Platelet inhibition is the main treatment strategy to prevent atherothrombotic complications after acute coronary syndrome or percutaneous coronary intervention. Despite dual antiplatelet therapy (DAPT) combining aspirin and a P2Y12 receptor inhibitor, high on-treatment platelet reactivity (HPR) persists in some patients due to poor response to treatment and is associated with ischemic risk. Tubulin acetylation has been pointed out as a hallmark of stable microtubules responsible for the discoid shape of resting platelets. However, the impact of antiplatelet treatments on this post-translational modification has never been studied. This study investigated whether tubulin acetylation differs according to antiplatelet therapy and on-treatment platelet reactivity. Platelets were isolated from arterial blood samples of 240 patients admitted for coronary angiography, and levels of α-tubulin acetylation on lysine 40 (α-tubulin K40 acetylation) were assessed by western blot. We show that platelet α-tubulin K40 acetylation was significantly increased in DAPT-treated patients. In addition, the proportion of patients with high levels of α-tubulin K40 acetylation was drastically reduced among DAPT-treated patients with HPR. Multivariate logistic regression confirmed that DAPT resulting in adequate platelet inhibition was strongly associated with elevated α-tubulin K40 acetylation. In conclusion, our study highlights the role of elevated platelet α-tubulin K40 acetylation as a marker of platelet inhibition in response to DAPT.Clinical trial registration: https://clinicaltrials.gov - NCT03034148.

What is the context? High on-treatment platelet reactivity due to dual antiplatelet therapy poor response is associated with thrombotic risk.Acetylation of α-tubulin K40 plays a crucial role in regulating platelet shape.High α-tubulin K40 acetylation is a hallmark of stable microtubules.What is new? α-tubulin K40 acetylation is increased in platelets from dual antiplatelet therapy-treated patients.High platelet α-tubulin K40 acetylation is mainly observed in clopidogrel-responsive patients.What is the impact? Elevated acetylated K40 α-tubulin could be used as a readout of adequate platelet inhibition in response to dual antiplatelet therapy.High α-tubulin K40 acetylation could contribute to maintaining the resting morphology of circulating platelets and therefore modify their capacity to be involved in thrombotic events.

Unsuspected diabetic ketoacidosis after myocardial infarction in a patient treated with SGLT2 inhibitor increased length of stay in the hospital: how can it be prevented? A case report.

Background: As the use of sodium-glucose co-transporter 2 inhibitors (SGLT2is) has expanded beyond glucose-lowering therapy in type 2 diabetes mellitus (T2DM), including chronic kidney disease and heart failure, there has also been an increase in reported cases of diabetic ketoacidosis (DKA) associated with SGLT2i. Case summary: A 77-year-old woman with T2DM presented to the emergency department with ST-segment elevation myocardial infarction (MI) complicated by atrial fibrillation. Her medications included empagliflozin, an SGLT2i, initiated for T2DM. Diabetic ketoacidosis was suspected on the basis of a large anion gap, despite a plasma glucose level below 200 mg/dL (11.1 mmol/L) and the absence of symptoms, including nausea and vomiting. Laboratory tests confirmed metabolic acidosis and high ketones. However, the diagnosis of euglycaemic DKA (eu-DKA) was delayed due to lack of symptoms and moderate hyperglycaemia. The patient was successfully treated according to DKA management guidelines. She was discharged on insulin, and SGLT2i was discontinued. Discussion: This is a case of asymptomatic eu-DKA after acute MI (AMI). We discuss the use of SGLT2is in AMI and arrhythmias from a review of the literature and the prophylaxis of eu-DKA. Regular monitoring of blood glucose and ketones should be performed in hospitalized T2DM patients treated with SGLT2i. The SGLT2i should be stopped as soon as possible in the event of critical illness or suspected DKA in the setting of an acute illness such as AMI. To help clinicians prevent this potentially fatal disease, we propose a flowchart for the prophylactic management of eu-DKA among inpatients.

Impact of early versus class I-triggered surgery on postoperative survival in severe aortic regurgitation: An observational study from the Aortic Valve Insufficiency and Ascending Aorta Aneurysm International Registry.

OBJECTIVES: Class I triggers for severe and chronic aortic regurgitation surgery mainly rely on symptoms or systolic dysfunction, resulting in a negative outcome despite surgical correction. Therefore, US and European guidelines now advocate for earlier surgery. We sought to determine whether earlier surgery leads to improved postoperative survival. METHODS: We evaluated the postoperative survival of patients who underwent surgery for severe aortic regurgitation in the international multicenter registry for aortic valve surgery, Aortic Valve Insufficiency and Ascending Aorta Aneurysm International Registry, over a median follow-up of 37 months. RESULTS: Among 1899 patients (aged 49 ± 15 years, 85% were male), 83% and 84% had class I indication according to the American Heart Association and European Society of Cardiology, respectively, and most were offered repair surgery (92%). Twelve patients (0.6%) died after surgery, and 68 patients died within 10 years after the procedure. Heart failure symptoms (hazard ratio, 2.60 [1.20-5.66], P = .016) and either left ventricular end-systolic diameter greater than 50 mm or left ventricular end-systolic diameter index greater than 25 mm/m2 (hazard ratio, 1.64 [1.05-2.55], P = .030) predicted survival independently over and above age, gender, and bicuspid phenotype. Therefore, patients who underwent surgery based on any class I trigger had worse adjusted survival. However, patients who underwent surgery while meeting early imaging triggers (left ventricular end-systolic diameter index 20-25 mm/m2 or left ventricular ejection fraction 50% to 55%) had no significant outcome penalty. CONCLUSIONS: In this international registry of severe aortic regurgitation, surgery when meeting class I triggers led to postoperative outcome penalty compared with earlier triggers (left ventricular end-systolic diameter index 20-25 mm/m2 or ventricular ejection fraction 50%-55%). This observation, which applies to expert centers where aortic valve repair is feasible, should encourage the global use of repair techniques and the conduction of randomized trials.

Mean platelet volume: a prognostic marker in heart failure with preserved ejection fraction.

Heart failure (HF) with preserved ejection fraction (HFpEF) is associated with high burden of comorbidities known to increase the mean platelet volume (MPV). This parameter has been associated with morbidity and mortality in HF. However, the role of platelets and the prognostic relevance of MPV in HFpEF remain largely unexplored. We aimed to evaluate the clinical usefulness of MPV as a prognostic marker in HFpEF. We prospectively enrolled 228 patients with HFpEF (79 ± 9 years; 66% females) and 38 controls of similar age and gender (78 ± 5 years; 63% females). All subjects underwent two-dimensional echocardiography and MPV measurements. Patients were followed-up for a primary end point of all-cause mortality or first HF hospitalization. The prognostic impact of MPV was determined using Cox proportional hazard models. Mean MPV was significantly higher in HFpEF patients compared with controls (MPV: 10.7 ± 1.1fL vs. 10.1 ± 1.1fL, p = .005). HFpEF patients (n = 56) with MPV >75th percentile (11.3 fL) displayed more commonly a history of ischemic cardiomyopathy. Over a median follow-up of 26 months, 136 HFpEF patients reached the composite endpoint. MPV >75th percentile was a significant predictor of the primary endpoint (HR: 1.70 [1.08; 2.67], p = .023) adjusted for NYHA class, chronic obstructive pulmonary disease, loop diuretics, renal function, and hemoglobin. We demonstrated that MPV was significantly higher in HFpEF patients compared with controls of similar age and gender. Elevated MPV was a strong and independent predictor of poor outcome in HFpEF patients and may be relevant for clinical use.

What is the context? Heart failure with preserved ejection fraction (HFpEF) is associated with several comorbidities known to increase the mean platelet volume (MPV).MPV is a measure of platelet size and a potential marker of platelet reactivity. An increased MPV results from an increased platelet turnover.MPV has been associated with morbidity and mortality from heart failure.No study has previously compared MPV between HFpEF and controls and investigated the prognostic relevance of MPV in HFpEF disease.What is new? In this study, we compared the MPV between HFpEF patients and controls of similar age and gender, prospectively enrolled between 2015 and 2021. We evaluated the prognostic role of elevated MPV in HFpEF patients.Our main results:The MPV was higher in HFpEF patients compared to controls of similar age and gender.HFpEF patients with elevated MPV displayed more commonly a history of ischemic cardiomyopathy.Elevated MPV was a strong and independent predictor of poor outcome in HFpEF patients.What is the impact? MPV may be relevant for clinical use to predict clinical outcome in HFpEF patients.Elevated MPV reflecting platelet activity supports the potential role of platelets in HFpEF's pathophysiology.

3D histopathology of stenotic aortic valve cusps using ex vivo microfocus computed tomography.

Background: Calcific aortic stenosis (AS) is the most prevalent heart valve disease in developed countries. The aortic valve cusps progressively thicken and the valve does not open fully due to the presence of calcifications. In vivo imaging, usually used for diagnosis, does not allow the visualization of the microstructural changes associated with AS. Methods: Ex vivo high-resolution microfocus computed tomography (microCT) was used to quantitatively describe the microstructure of calcified aortic valve cusps in full 3D. As case study in our work, this quantitative analysis was applied to normal-flow low-gradient severe AS (NF-LG-SAS), for which the medical prognostic is still highly debated in the current literature, and high-gradient severe AS (HG-SAS). Results: The volume proportion of calcification, the size and number of calcified particles and their density composition was quantified. A new size-based classification considering small-sized particles that are not detected with in vivo imaging was defined for macro-, meso- and microscale calcifications. Volume and thickness of aortic valve cusps, including the complete thickness distribution, were also determined. Moreover, changes in the cusp soft tissues were also visualized with microCT and confirmed by scanning electron microscopy images of the same sample. NF-LG-SAS cusps contained lower relative amount of calcifications than HG-SAS. Moreover, the number and size of calcified objects and the volume and thickness of the cusps were also lower in NF-LG-SAS cusps than in HG-SAS. Conclusions: The application of high-resolution ex vivo microCT to stenotic aortic valve cusps provided a quantitative description of the general structure of the cusps and of the calcifications present in the cusp soft tissues. This detailed description could help in the future to better understand the mechanisms of AS.

Dexamethasone Modulates the Cytokine Response but Not COVID-19-Induced Coagulopathy in Critically Ill.

Severe forms of coronavirus 2019 (COVID-19) disease are caused by an exaggerated systemic inflammatory response and subsequent inflammation-related coagulopathy. Anti-inflammatory treatment with low dose dexamethasone has been shown to reduce mortality in COVID-19 patients requiring oxygen therapy. However, the mechanisms of action of corticosteroids have not been extensively studied in critically ill patients in the context of COVID-19. Plasma biomarkers of inflammatory and immune responses, endothelial and platelet activation, neutrophil extracellular trap formation, and coagulopathy were compared between patients treated or not by systemic dexamethasone for severe forms of COVID-19. Dexamethasone treatment significantly reduced the inflammatory and lymphoid immune response in critical COVID-19 patients but had little effect on the myeloid immune response and no effect on endothelial activation, platelet activation, neutrophil extracellular trap formation, and coagulopathy. The benefits of low dose dexamethasone on outcome in critical COVID-19 can be partially explained by a modulation of the inflammatory response but not by reduction of coagulopathy. Future studies should explore the impact of combining dexamethasone with other immunomodulatory or anticoagulant drugs in severe COVID-19.

Enhanced protein acetylation initiates fatty acid-mediated inhibition of cardiac glucose transport.

Fatty acids (FAs) rapidly and efficiently reduce cardiac glucose uptake in the Randle cycle or glucose-FA cycle. This fine-tuned physiological regulation is critical to allow optimal substrate allocation during fasted and fed states. However, the mechanisms involved in the direct FA-mediated control of glucose transport have not been totally elucidated yet. We previously reported that leucine and ketone bodies, other cardiac substrates, impair glucose uptake by increasing global protein acetylation from acetyl-CoA. As FAs generate acetyl-CoA as well, we postulated that protein acetylation is enhanced by FAs and participates in their inhibitory action on cardiac glucose uptake. Here, we demonstrated that both palmitate and oleate promoted a rapid increase in protein acetylation in primary cultured adult rat cardiomyocytes, which correlated with an inhibition of insulin-stimulated glucose uptake. This glucose absorption deficit was caused by an impairment in the translocation of vesicles containing the glucose transporter GLUT4 to the plasma membrane, although insulin signaling remained unaffected. Interestingly, pharmacological inhibition of lysine acetyltransferases (KATs) prevented this increase in protein acetylation and glucose uptake inhibition induced by FAs. Similarly, FA-mediated inhibition of insulin-stimulated glucose uptake could be prevented by KAT inhibitors in perfused hearts. To summarize, enhanced protein acetylation can be considered as an early event in the FA-induced inhibition of glucose transport in the heart, explaining part of the Randle cycle.NEW & NOTEWORTHY Our results show that cardiac metabolic overload by oleate or palmitate leads to increased protein acetylation inhibiting GLUT4 translocation to the plasma membrane and glucose uptake. This observation suggests an additional regulation mechanism in the physiological glucose-FA cycle originally discovered by Randle.

Cryogenic contrast-enhanced microCT enables nondestructive 3D quantitative histopathology of soft biological tissues.

Biological tissues comprise a spatially complex structure, composition and organization at the microscale, named the microstructure. Given the close structure-function relationships in tissues, structural characterization is essential to fully understand the functioning of healthy and pathological tissues, as well as the impact of possible treatments. Here, we present a nondestructive imaging approach to perform quantitative 3D histo(patho)logy of biological tissues, termed Cryogenic Contrast-Enhanced MicroCT (cryo-CECT). By combining sample staining, using an X-ray contrast-enhancing staining agent, with freezing the sample at the optimal freezing rate, cryo-CECT enables 3D visualization and structural analysis of individual tissue constituents, such as muscle and collagen fibers. We applied cryo-CECT on murine hearts subjected to pressure overload following transverse aortic constriction surgery. Cryo-CECT allowed to analyze, in an unprecedented manner, the orientation and diameter of the individual muscle fibers in the entire heart, as well as the 3D localization of fibrotic regions within the myocardial layers. We foresee further applications of cryo-CECT in the optimization of tissue/food preservation and donor banking, showing that cryo-CECT also has clinical and industrial potential.

Mitochondrial Protein Cox7b Is a Metabolic Sensor Driving Brain-Specific Metastasis of Human Breast Cancer Cells.

Distant metastases are detrimental for cancer patients, but the increasingly early detection of tumors offers a chance for metastasis prevention. Importantly, cancers do not metastasize randomly: depending on the type of cancer, metastatic progenitor cells have a predilection for well-defined organs. This has been theorized by Stephen Paget, who proposed the "seed-and-soil hypothesis", according to which metastatic colonization occurs only when the needs of a given metastatic progenitor cell (the seed) match with the resources provided by a given organ (the soil). Here, we propose to explore the seed-and-soil hypothesis in the context of cancer metabolism, thus hypothesizing that metastatic progenitor cells must be capable of detecting the availability of metabolic resources in order to home in a secondary organ. If true, it would imply the existence of metabolic sensors. Using human triple-negative MDA-MB-231 breast cancer cells and two independent brain-seeking variants as models, we report that cyclooxygenase 7b (Cox7b), a structural component of Complex IV of the mitochondrial electron transport chain, belongs to a probably larger family of proteins responsible for breast cancer brain tropism in mice. For metastasis prevention therapy, this proof-of-principle study opens a quest for the identification of therapeutically targetable metabolic sensors that drive cancer organotropism.

NETosis and Nucleosome Biomarkers in Septic Shock and Critical COVID-19 Patients: An Observational Study.

Background: Neutrophil extracellular traps' (NETs') formation is a mechanism of defense that neutrophils deploy as an alternative to phagocytosis, to constrain the spread of microorganisms. Aim: The aim was to evaluate biomarkers of NETs' formation in a patient cohort admitted to intensive care unit (ICU) due to infection. Methods: Forty-six septic shock patients, 22 critical COVID-19 patients and 48 matched control subjects were recruited. Intact nucleosomes containing histone 3.1 (Nu.H3.1), or citrullinated histone H3R8 (Nu.Cit-H3R8), free citrullinated histone (Cit-H3), neutrophil elastase (NE) and myeloperoxidase (MPO) were measured. Results: Significant differences in Nu.H3.1 and NE levels were observed between septic shock and critical COVID-19 subjects as well as with controls (p-values < 0.05). The normalization of nucleosome levels according to the neutrophil count improved the discrimination between septic shock and critical COVID-19 patients. The ratio of Nu.Cit-H3R8 to Nu.H3.1 allowed the determination of nucleosome citrullination degree, presumably by PAD4. Conclusions: H3.1 and Cit-H3R8 nucleosomes appear to be interesting markers of global cell death and neutrophil activation when combined. Nu.H3.1 permits the evaluation of disease severity and differs between septic shock and critical COVID-19 patients, reflecting two distinct potential pathological processes in these conditions.

Prediction of Left Atrial Fibrosis and Success of Catheter Ablation by Speckle Tracking Echocardiography in Patients Imaged in Persistent Atrial Fibrillation.

Background: Non-invasive evaluation of left atrial structural and functional remodeling should be considered in all patients with persistent atrial fibrillation (AF) to optimal management. Speckle tracking echocardiography (STE) has been shown to predict AF recurrence after catheter ablation; however in most studies, patients had paroxysmal AF, and STE was performed while patients were in sinus rhythm. Aim: The aim of this study was to evaluate the ability of STE parameters acquired during persistent AF to assess atrial fibrosis measured by low voltage area, and to predict maintenance of sinus rhythm of catheter ablation. Methods: A total of 94 patients (69 men, 65 ± 9 years) with persistent AF prospectively underwent measurement of Global Peak Atrial Longitudinal Strain (GPALS), indexed LA Volume (LAVI), E/e' ratio, and LA stiffness index (the ratio of E/e' to GPALS) by STE prior to catheter ablation, while in AF. Low-voltage area (LVA) was assessed by electro-anatomical mapping and categorized into absent, moderate (>0 to <15%), and high (≥15%) atrial extent. AF recurrence was evaluated after 3 months of blanking. Results: Multivariable regression showed that LAVI, GPALS, and LA stiffness independently predicted LVA extent after correcting for age, glomerular filtration rate, and CHA2DS2-VASc score. Of all the parameters, LA stiffness index had the highest diagnostic accuracy (AUC 0.85), allowing using a cut-off value ≥0.7 to predict moderate or high LVA with 88% sensitivity and 47% specificity, respectively. In multivariable Cox analysis, both GPALS and LA stiffness were able to significantly improve the c statistic to predict AF recurrence (n = 40 over 9 months FU) over CHARGE-AF (p < 0.001 for GPALS and p = 0.01 for LA stiffness) or CHA2DS2-VASc score (p < 0.001 for GPALS and p = 0.02 for LA stiffness). GPALS and LA stiffness also improved the net reclassification index (NRI) over the CHARGE-AF index (NRI 0.67, 95% CI [0.33-1.13] for GPALS and NRI 0.73, 95% CI [0.12-0.91] for LA stiffness, respectively), and over the CHA2DS2-VASc score (NRI 0.43, 95% CI [-0.14 to 0.69] for GPALS and NRI 0.52, 95% CI [0.10-0.84], respectively) for LA stiffness to predict AF recurrence at 9 months. Conclusion: STE parameters acquired during AF allow prediction of LVA extent and AF recurrence in patients with persistent AF undergoing catheter ablation. Therefore, STE could be a valuable approach to select candidates for catheter ablation.

The intra-mitochondrial O-GlcNAcylation system rapidly modulates OXPHOS function and ROS release in the heart.

Protein O-GlcNAcylation is increasingly recognized as an important cellular regulatory mechanism, in multiple organs including the heart. However, the mechanisms leading to O-GlcNAcylation in mitochondria and the consequences on their function remain poorly understood. In this study, we use an in vitro reconstitution assay to characterize the intra-mitochondrial O-GlcNAc system without potential cytoplasmic confounding effects. We compare the O-GlcNAcylome of isolated cardiac mitochondria with that of mitochondria acutely exposed to NButGT, a specific inhibitor of glycoside hydrolase. Amongst the 409 O-GlcNAcylated mitochondrial proteins identified, 191 display increased O-GlcNAcylation in response to NButGT. This is associated with enhanced Complex I (CI) activity, increased maximal respiration in presence of pyruvate-malate, and a striking reduction of mitochondrial ROS release, which could be related to O-GlcNAcylation of specific subunits of ETC complexes (CI, CIII) and TCA cycle enzymes. In conclusion, our work underlines the existence of a dynamic mitochondrial O-GlcNAcylation system capable of rapidly modifying mitochondrial function.