Usefulness of Serum Biomarkers of Endothelial Glycocalyx Damage in Prognosis of Decompensated Patients with Heart Failure with Reduced Ejection Fraction

The Endothelial Glycocalyx in Pig-to-Baboon Cardiac Xenotransplantation-First Insights

Cardiac xenotransplantation has seen remarkable success in recent years and is emerging as the most promising alternative to human cardiac allotransplantation. Despite these achievements, acute vascular rejection still presents a challenge for long-term xenograft acceptance and new insights into innate and adaptive immune responses as well as detailed characterizations of signaling pathways are necessary. In allotransplantation, endothelial cells and their sugar-rich surface-the endothelial glycocalyx-are known to influence organ rejection. In xenotransplantation, however, only in vitro data exist on the role of the endothelial glycocalyx so far. Thus, in the current study, we analyzed the changes of the endothelial glycocalyx components hyaluronan, heparan sulfate and syndecan-1 after pig-to-baboon cardiac xenotransplantations in the perioperative (n = 4) and postoperative (n = 5) periods. These analyses provide first insights into changes of the endothelial glycocalyx after pig-to-baboon cardiac xenotransplantation and show that damage to the endothelial glycocalyx seems to be comparable or even less pronounced than in similar human settings when current strategies of cardiac xenotransplantation are applied. At the same time, data from the experiments where current strategies, like non-ischemic preservation, growth inhibition or porcine cytomegalovirus (a porcine roseolovirus (PCMV/PRV)) elimination could not be applied indicate that damage of the endothelial glycocalyx also plays an important role in cardiac xenotransplantation.

Insights into the Molecular Mechanism of Endothelial Glycocalyx Dysfunction during Heart Surgery

The endothelial glycocalyx (EGC) is a layer of proteoglycans (associated with glycosaminoglycans) and glycoproteins, which adsorbs plasma proteins on the luminal surface of endothelial cells. Its main function is to participate in separating the circulating blood from the inner layers of the vessels and the surrounding tissues. Physiologically, the EGC stimulates mechanotransduction, the endothelial charge, thrombocyte adhesion, leukocyte tissue recruitment, and molecule extravasation. Hence, severe impairment of the EGC has been implicated in various pathological conditions, including sepsis, diabetes, chronic kidney disease, inflammatory disorders, hypernatremia, hypervolemia, atherosclerosis, and ischemia/reperfusion injury. Moreover, alterations in EGC have been associated with altered responses to therapeutic interventions in conditions such as cardiovascular diseases. Investigation into the function of the glycocalyx has expanded knowledge about vascular disorders and indicated the need to consider new approaches in the treatment of severe endothelial dysfunction. This review aims to present the current understanding of the molecular mechanisms underlying cardiovascular diseases and to elucidate the impact of heart surgery on EGC dysfunction.

Endogenous Dysregulation of Thromboinflammatory Biomarkers in End-Stage Renal Disease, and Their Amplification by Heart Failure

In patients with end-stage renal disease (ESRD), heart failure with reduced ejection fraction (HFrEF) is a common comorbidity. Thromboinflammatory processes in both conditions represent complex pathophysiology, demonstrated by dysregulation of thromboinflammatory biomarkers, and commonly resulting in the combined pathology of cardiorenal syndrome. We sought to investigate the effects of HFrEF on these biomarkers in patients with ESRD, and observe the relationship to mortality. Blood samples from 73 patients with ESRD (mean age 67 ± 13 years, 56% male) and 40 healthy controls were analyzed via enzyme-linked immunosorbent assay and other chromogenic methods for angiopoietin-2 (Ang2), endogenous glycosaminoglycans, fatty acid binding protein, interleukin-6, lipopolysaccharide, free fatty acids, NT-pro B-type natriuretic peptide, tumor necrosis factor α, vascular endothelial growth factor, and von Willebrand factor. Patients were stratified into those with or without HFrEF (EF < 50%). Patients had highly prevalent comorbidities including coronary artery disease 46%, diabetes 69%, hypertension 97%, and smoking 49%. Most biomarkers were upregulated in ESRD compared to controls. Patients with HFrEF and ESRD had greater interleukin-6 and NT-pro B-type natriuretic peptide and lesser lipopolysaccharide compared to ESRD only. Spearman correlations between most biomarkers were increased in HFrEF + ESRD over ESRD only. Ang-2 was associated with mortality in this cohort. The dysregulation of thromboinflammation in ESRD is somewhat amplified in comorbid HFrEF. Correlation among biomarkers in this cohort indicates the mechanisms of thromboinflammatory biomarker generation in ESRD and HFrEF share an integrative process. Ang2, interleukin-6, and lipopolysaccharide show promise as biomarkers for risk stratification among patients with both HFrEF and ESRD.

Molecular Mechanisms and Therapeutic Implications of Endothelial Dysfunction in Patients with Heart Failure

Heart failure is a complex medical syndrome that is attributed to a number of risk factors; nevertheless, its clinical presentation is quite similar among the different etiologies. Heart failure displays a rapidly increasing prevalence due to the aging of the population and the success of medical treatment and devices. The pathophysiology of heart failure comprises several mechanisms, such as activation of neurohormonal systems, oxidative stress, dysfunctional calcium handling, impaired energy utilization, mitochondrial dysfunction, and inflammation, which are also implicated in the development of endothelial dysfunction. Heart failure with reduced ejection fraction is usually the result of myocardial loss, which progressively ends in myocardial remodeling. On the other hand, heart failure with preserved ejection fraction is common in patients with comorbidities such as diabetes mellitus, obesity, and hypertension, which trigger the creation of a micro-environment of chronic, ongoing inflammation. Interestingly, endothelial dysfunction of both peripheral vessels and coronary epicardial vessels and microcirculation is a common characteristic of both categories of heart failure and has been associated with worse cardiovascular outcomes. Indeed, exercise training and several heart failure drug categories display favorable effects against endothelial dysfunction apart from their established direct myocardial benefit.