PCYT2-regulated lipid biosynthesis is critical to muscle health and ageing

Muscle degeneration is the most prevalent cause for frailty and dependency in inherited diseases and ageing. Elucidation of pathophysiological mechanisms, as well as effective treatments for muscle diseases, represents an important goal in improving human health. Here, we show that the lipid synthesis enzyme phosphatidylethanolamine cytidyltransferase (PCYT2/ECT) is critical to muscle health. Human deficiency in PCYT2 causes a severe disease with failure to thrive and progressive weakness. pcyt2-mutant zebrafish and muscle-specific Pcyt2-knockout mice recapitulate the participant phenotypes, with failure to thrive, progressive muscle weakness and accelerated ageing. Mechanistically, muscle Pcyt2 deficiency affects cellular bioenergetics and membrane lipid bilayer structure and stability. PCYT2 activity declines in ageing muscles of mice and humans, and adeno-associated virus-based delivery of PCYT2 ameliorates muscle weakness in Pcyt2-knockout and old mice, offering a therapy for individuals with a rare disease and muscle ageing. Thus, PCYT2 plays a fundamental and conserved role in vertebrate muscle health, linking PCYT2 and PCYT2-synthesized lipids to severe muscle dystrophy and ageing.

Predisposing and Precipitating Risk Factors for Delirium in Elderly Patients Admitted to a Cardiology Ward: An Observational Cohort Study in 1,042 Patients

Aim: Although the risk factors for delirium in general medicine are well-established, their significance in cardiac diseases remains to be determined. Therefore, we evaluated the predisposing and precipitating risk factors in patients hospitalized with acute and chronic heart disease.

Methods and Results: In this observational cohort study, 1,042 elderly patients (≥65 years) admitted to cardiology wards, 167 with and 875 without delirium, were included. The relevant sociodemographic and cardiac- and medical-related clusters were assessed by simple and multiple regression analyses and prediction models evaluating their association with delirium. The prevalence of delirium was 16.0%. The delirious patients were older (mean 80 vs. 76 years; p < 0.001) and more often institutionalized prior to admission (3.6 vs. 1.4%, p = 0.05), hospitalized twice as long (12 ± 10 days vs. 7 ± 7 days; p < 0.001), and discharged more often to nursing homes (4.8 vs. 0.6%, p < 0.001) or deceased (OR, 2.99; 95% CI, 1.53–5.85; p = 0.003). The most relevant risk factor was dementia (OR, 18.11; 95% CI, 5.77–56.83; p < 0.001), followed by history of stroke (OR, 6.61; 95% CI 1.35–32.44; p = 0.020), and pressure ulcers (OR, 3.62; 95% CI, 1.06–12.35; p = 0.040). The predicted probability for developing delirium was highest in patients with reduced mobility and institutionalization prior to admission (PP = 31.2%, p = 0.001). Of the cardiac diseases, only valvular heart disease (OR, 1.57; 95% CI, 1.01–2.44; p = 0.044) significantly predicted delirium. The patients undergoing cardiac interventions did not have higher rates of delirium (OR, 1.39; 95% CI 0.91–2.12; p = 0.124).

Conclusion: In patients admitted to a cardiology ward, age-related functional and cognitive impairment, history of stroke, and pressure ulcers were the most relevant risk factors for delirium. With regards to specific cardiological factors, only valvular heart disease was associated with risk for delirium. Knowing these factors can help cardiologists to facilitate the early detection and management of delirium.

Endothelial dysfunction in COVID-19: Current findings and therapeutic implications

Coronavirus disease 2019 (COVID-19) increases the risk of several non-pulmonary complications such as acute myocardial injury, renal failure or thromboembolic events. A possible unifying explanation for these phenomena may be the presence of profound endothelial dysfunction and injury. This review provides an overview on the association of endothelial dysfunction with COVID-19 and its therapeutic implications. Endothelial dysfunction is a common feature of the key comorbidities that increase risk for severe COVID-19 such as hypertension, obesity, diabetes mellitus, coronary artery disease or heart failure. Preliminary studies indicate that vascular endothelial cells can be infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and evidence of widespread endothelial injury and inflammation is found in advanced cases of COVID-19. Prior evidence has established the crucial role of endothelial cells in maintaining and regulating vascular homeostasis and blood coagulation. Aggravation of endothelial dysfunction in COVID-19 may therefore impair organ perfusion and cause a procoagulatory state resulting in both macro- and microvascular thrombotic events. Angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs) and statins are known to improve endothelial dysfunction. Data from smaller observational studies and other viral infections suggests a possible beneficial effect in COVID-19. Other treatments that are currently under investigation for COVID-19 may also act by improving endothelial dysfunction in patients. Focusing therapies on preventing and improving endothelial dysfunction could improve outcomes in COVID-19. Several clinical trials are currently underway to explore this concept.

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New evidence implicates endothelial dysfunction in the pathophysiology of COVID-19.

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It may explain complications such as multi-organ damage or thrombotic events.

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Targeted interventions such as RAS inhibitors or statins may improve outcomes.

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Studies on interventions that affect endothelial dysfunction are underway in COVID-19.

Abstract 251: Neuregulin Administration Stimulates Cardiomyocyte Proliferation In Neonatal Mice And In Myocardium From Human Infants

Background: Regenerative strategies have the potential to transform heart failure therapies. Cell transplantation strategies have shown effectiveness and safety in clinical trials. A complementary strategy is based on directly stimulating the proliferation of endogenous cardiomyocytes. We have demonstrated that administration of the growth factor neuregulin (rNRG1), which has passed phase 2 testing, stimulates cardiomyocyte proliferation and improves myocardial repair in adult animal models. Since cardiomyocyte proliferation is active during myocardial growth, we hypothesized that NRG1 may be more effective in growing animals and humans.

Methods: We developed a myocardial injury model (cryoinjury) in neonatal mice that recapitulates scar formation seen in infants with congenital heart disease (CHD). In contrast with ligation of the left anterior descending coronary artery (LAD), cryoinjury reduced cardiomyocyte cell cycle activity. We used this model to evaluate the effectiveness of rNRG1 administration. To assess the ability of rNRG1 to stimulate human cardiomyocyte proliferation, we developed an organotypic culture system for myocardium from infants with CHD.

Results: Administration of NRG1 resulted in a 2-fold increase in cardiomyocyte cell cycle activity at 10 days post injury (dpi). After neonatal cryoinjury in mice, administration of rNRG1 from birth to 30 days of life significantly improved the ejection fraction, which was sustained for 30 days after the cessation of rNRG1 administration. In contrast, administration of NRG1 four to 34 days after cryoinjury transiently reduced scar formation, and transiently improved myocardial structure and function. In myocardium from infants with Tetralogy of Fallot (ToF) less than 6 months of age (n = 6), rNRG1 induced cardiomyocyte proliferation.

Conclusions: These results indicate that stimulating cardiomyocyte proliferation may be clinically effective in human infants with heart disease, a population in whom a significant and unmet need exists.

Myocardial ischaemia-reperfusion injury in haematopoietic cell-restricted beta1 integrin knockout mice

Evidence indicates that the intercellular adhesion molecule-1 and its counter-receptor beta2 integrin are cardioprotective proteins during myocardial ischaemia-reperfusion, but no data are available concerning the role of blood cell beta1 integrins in this process. We studied the effects of temporary myocardial ischaemia and reperfusion in blood cell-restricted beta1 integrin knockout mice (beta1(-/-)). The left descending coronary artery in conditional beta1(-/-) integrin (beta1(-/-)), beta1 integrin +/+ (beta1(+/+)) and beta1 integrin -/- bone marrow chimeric (beta1(-/-) BM) mice was ligated for 30 min, followed by reperfusion of either 3 h or 3 weeks. Plasma levels of troponin T were evaluated as an index of cardiac cellular damage. The histological evaluation of tissue damage was performed with Haematoxylin and Eosin stained sections. Cell infiltrations in the ischaemic area were investigated by immunofluorescence studies. It was found that plasma troponin T was at a similar level in beta1(-/-), beta1(+/+) and beta1(-/-) BM mice treated with 30 min ischaemia and 3 h reperfusion. Histological analysis showed that ischaemia-reperfusion resulted in marked myocardial injury in all groups of animals, but the damage score of the hearts was not significantly different between beta1(-/-), beta1(+/+) and beta1(-/-) BM mice after 3 h of reperfusion following 30 min of ischaemia (2.8 +/- 0.5, 2.6 +/- 0.5 and 2.8 +/- 0.6, respectively, n.s.). Furthermore, no difference in scar sizes in ischaemia-injured hearts was found 3 weeks after ischaemia. Semi-quantification of cells demonstrated that, compared with beta1(+/+) mice, the number of infiltrating neutrophils was significantly reduced in beta1(-/-) and beta1(-/-) BM mice, whereas MAC-1(CD11b/CD18)-positive cells in the ischaemic regions were similar in myocardial tissues of all groups. We conclude that absence of beta1 integrin expression in haematopoietic cells results in reduced neutrophil infiltration in the ischaemic regions, but does not influence myocardial damage of ischaemic hearts.