Endothelial barrier dysfunction in systemic inflammation is mediated by soluble VE-cadherin interfering VE-PTP signaling

Breakdown of endothelial barrier integrity determines organ dysfunction and outcome of patients with sepsis. Increased levels of soluble vascular endothelial (VE)-cadherin fragments (sVE-cadherin) have previously been linked with inflammation-induced loss of endothelial barrier function. We provide evidence for a causative role of sVE-cadherin to induce loss of endothelial barrier function. In patients with sepsis, sVE-cadherin levels were associated with organ dysfunction and the need for volume resuscitation. Similarly, LPS-induced systemic inflammation in rats with microvascular dysfunction was paralleled by augmented sVE-cadherin levels. Newly generated recombinant human sVE-cadherin (extracellular domains EC1-5) induced loss of endothelial barrier function in both human microvascular endothelial cells in vitro and in rat mesenteric microvessels in vivo and reduced microcirculatory flow. sVE-cadherinEC1-5 disturbed VE-cadherin-mediated adhesion and perturbed VE-protein tyrosine phosphatase (VE-PTP)/VE-cadherin interaction resulting in RhoGEF1-mediated RhoA activation. VE-PTP inhibitor AKB9778 and Rho-kinase inhibitor Y27632 blunted all sVE-cadherinEC1-5-induced effects, which uncovers a pathophysiological role of sVE-cadherin via dysbalanced VE-PTP/RhoA signaling.

External validation of the REMEMBER score

Background

The use of venoarterial extracorporeal membrane oxygenation (VA-ECMO) after coronary artery bypass grafting (CABG) is associated with high in-hospital mortality rates. The pRedicting mortality in patients undergoing venoarterial Extracorporeal MEMBrane oxygenation after coronary artEry bypass gRafting (REMEMBER) score has been created to predict in-hospital mortality in this subgroup of patients. The aim of this study is to externally validate the REMEMBER score.

Methods

All CABG patients who received VA-ECMO during or after the operation at our center between 01/2012 and 12/2021 were included in the analysis. Discrimination was assessed using concordance statistics, visualized by ROC curve analysis. Calibration-in-the-large and Calibration slope were tested separately.

Results

A total of 107 patients (male: n = 78, 72.9%) were included in this study. The in-hospital mortality rate in our cohort was 45.8% compared with 55% in the original study. The REMEMBER score median predicted mortality rate was 52% (76.9-36%). However, the REMEMBER score showed low discriminative ability [AUC: 0.623 (p = 0.0244; 95% CI = 0.524-0.715)] and inaccurate calibration (intercept = 0.25074; p = 0.0195; slope = 0.39504; p = 0.0303), indicating poor performance.

Conclusions

The REMEMBER score did not predict in-hospital mortality and was therefore not applicable in our cohort of patients. Additional external validation studies in a multicenter setting are therefore advisable.

A model of porcine polymicrobial septic shock

BACKGROUND

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Mortality of patients with sepsis is high and largely unchanged throughout the past decades. Animal models have been widely used for the study of sepsis and septic shock, but translation into effective treatment regimes in the clinic have mostly failed. Pigs are considered as suitable research models for human diseases due to their high comparability and similarity to human anatomy, genetics, and the immune system. We here evaluated the previously reported models of septic shock in pigs and established a novel model of polymicrobial sepsis that meets the clinical criteria of septic shock in pigs.

MATERIALS AND METHODS

The literature search was performed using the keywords "pig", "sepsis" and "septic shock". For the establishment of septic shock in n = 10 German landrace pigs, mechanical ventilation was initiated, central venous and arterial lines and invasive hemodynamic monitoring via pulse contour cardiac output measurement (PiCCO) established. Peritoneal polymicrobial faecal sepsis was induced by application of 3 g/kg body weight faeces into the abdominal cavity. Septic shock was defined according to the third international consensus definitions (Sepsis-3). Upon shock, pigs underwent the 1-h bundle for the treatment of human sepsis. Cytokine levels were measured by ELISA.

RESULTS

Published porcine sepsis models exhibited high methodological variability and did not meet the clinical criteria of septic shock. In our model, septic shock developed after an average of 4.8 ± 0.29 h and was associated with a reproducible drop in blood pressure (mean arterial pressure 54 ± 1 mmHg) and significant hyperlactatemia (3.76 ± 0.65 mmol/L). Septic shock was associated with elevated levels of interleukin-6 (IL6) and initial cardiac depression followed by a hyperdynamic phase with significant loss of systemic vascular resistance index after initial resuscitation. In addition, organ dysfunction (acute kidney injury) occurred.

CONCLUSIONS

We here established a model of septic shock in pigs that meets the clinical criteria of septic shock utilized in human patients. Our model may thus serve as a reference for clinically relevant sepsis research in pigs.

Procalcitonin mediates vascular dysfunction in obesity

AIMS

Obesity is accompanied by a chronic low-grade inflammation associated with endothelial dysfunction and vascular complications. Procalcitonin is a marker of inflammation, secreted by adipose tissue and elevated in obese subjects. We here investigated whether visceral or perivascular fat-derived procalcitonin is a target to improve obesity-induced endothelial dysfunction.

MATERIALS AND METHODS

Procalcitonin expression was identified by Western blot. Murine endothelial cells were isolated using CD31-antibody-coated magnetic beads and reactive oxygen species and nitric oxide (NO) determined by H2DCF- or DAF-FM diacetate loading. Endothelium-dependent vasorelaxation was analyzed using pressure myography of murine arterioles. Calcitonin gene-related peptide (CGRP) was used to activate the calcitonin receptor-like receptor (CRLR)/RAMP1 complex and olcegepant or the dipeptidyl-peptidase 4 (DPP4) inhibitor sitagliptin to block procalcitonin signaling or activation.

KEY FINDINGS

In addition to visceral adipose tissue, procalcitonin was present in perivascular and epicardial tissue. In concentrations typical for obesity, procalcitonin doubled reactive oxygen species formation and decreased endothelial nitric oxide production in murine endothelial cells. Intravenous delivery of procalcitonin to mice in obesity-associated concentrations impaired endothelium-dependent vasorelaxation in a CRLR/RAMP1-dependent manner and antagonized CGRP-induced endothelial NO release in vitro. Use of CRLR/RAMP1-receptor antagonist olcegepant counteracted procalcitonin effects on vasodilation, nitric oxide production and reactive oxygen species formation. Similarly, blocking procalcitonin activation by the DPP4 inhibitor sitagliptin antagonized endothelial procalcitonin effects.

SIGNIFICANCE

Procalcitonin, liberated either from visceral or perivascular adipose tissue, contributes to endothelial dysfunction by antagonizing CGRP signaling in obesity. Targeting hyperprocalcitonemia may be a means to preserve endothelial function and reduce comorbidity burden in obese subjects.

Targeting Procalcitonin Protects Vascular Barrier Integrity

RATIONALE

Capillary leakage frequently occurs during sepsis and after major surgery and is associated with microvascular dysfunction and adverse outcome. Procalcitonin is a well-established biomarker in inflammation without known impact on vascular integrity.

OBJECTIVE

We determined how procalcitonin induces endothelial hyperpermeability and how targeting procalcitonin protects vascular barrier integrity.

METHODS

In a prospective observational clinical study, procalcitonin levels were assessed in 50 cardiac surgery patients and correlated to postoperative fluid and vasopressor requirements along with sublingual microvascular functionality. Effects of the procalcitonin signaling pathway on endothelial barrier and adherens junctional integrity were characterized in vitro and verified in mice. Inhibition of procalcitonin activation by dipeptidyl-peptidase 4 (DPP4) was evaluated in murine polymicrobial sepsis and clinically verified in cardiac surgery patients chronically taking the DPP4 inhibitor sitagliptin.

MEASUREMENTS AND MAIN RESULTS

Elevated postoperative procalcitonin levels identified patients with 2-fold increased fluid requirements (P<0.01), 1.8-fold higher vasopressor demand (P<0.05) and compromised microcirculation (reduction to 63.5±2.8% of perfused vessels, P<0.05). Procalcitonin induced 1.4-fold endothelial and 2.3-fold pulmonary capillary permeability (both P<0.001) by destabilizing VE-cadherin. Procalcitonin effects were dependent on activation by DPP4 and targeting the procalcitonin receptor or DPP4 during sepsis-induced hyperprocalcitonemia reduced capillary leakage by 54±10.1% and 60.4±6.9% (both P<0.01), respectively. Sitagliptin prior to cardiac surgery was associated with augmented microcirculation (74.1±1.7% vs. 68.6±1.9% perfused vessels in sitagliptin non-medicated patients, P<0.05) and 2.3-fold decreased fluid (P<0.05) and 1.8-fold reduced vasopressor demand postoperatively (P<0.05).

CONCLUSION

Targeting procalcitonin's action on the endothelium is a feasible means to preserve vascular integrity during systemic inflammation associated with hyperprocalcitonemia.

Development of heart failure with preserved ejection fraction in type 2 diabetic mice is ameliorated by preserving vascular function

AIMS

Heart failure with preserved ejection fraction (HFpEF) is associated with endothelial dysfunction and is frequent in people with type 2 diabetes mellitus. In diabetic patients, increased levels of the eicosanoid 12-hydroxyeicosatetraenoic acid (12-HETE) are linked to vascular dysfunction. Here, we aimed to identify the importance of 12-HETE in type 2 diabetic patients exhibiting diastolic dysfunction, and mice exhibiting HFpEF and whether targeting 12-HETE is a means to ameliorate HFpEF progression by improving vascular function in diabetes.

MATERIAL AND METHODS

Subjects with diagnosed type 2 diabetes mellitus and reported diastolic dysfunction or healthy controls were recruited and 12(S)-HETE levels determined by ELISA. 12(S)-HETE levels were determined in type 2 diabetic, leptin receptor deficient mice (LepRdb/db) and HFpEF verified by echocardiography. Mitochondrial function, endothelial function and capillary density were assessed using Seahorse technique, pressure myography and immunohistochemistry in LepRdb/db or non-diabetic littermate controls. 12/15Lo generation was inhibited using ML351 and 12(S)-HETE action by using the V1-cal peptide.

KEY FINDINGS

Endothelium-dependent vasodilation and mitochondrial functional capacity both improved in response to either application of ML351 or the V1-cal peptide. Correlating to improved vascular function, mice treated with either pharmacological agent exhibited improved diastolic filling and left ventricular relaxation that correlated with increased myocardial capillary density.

SIGNIFICANCE

Our results suggest that 12-HETE may serve as a biomarker indicating endothelial dysfunction and the resulting cardiovascular consequences such as HFpEF in type 2 diabetic patients. Antagonizing 12-HETE is a potent means to causally control HFpEF development and progression in type 2 diabetes by preserving vascular function.

Extubation in the Operating Room After Fontan Procedure: Does It Make a Difference?

Early extubation appears to have beneficial effects on the Fontan circulation. The goal of this study was to assess the impact of extubation on the operating table in comparison with extubation during the first hours after Fontan operation (FO) on the early postoperative course. Between 2013 and 2016, 114 children with a single ventricle heart malformations (mean age, 3.8 ± 2.3 years) underwent FO: 60 patients were extubated in the operating room (ORE) and 54 in the intensive care unit (ICUE) in the median time of 195 min (range 30-515 min) after procedure. Pre-, peri-, and postoperative records were retrospectively analyzed. The hospital survival rate was 100%. One patient from the ORE group needed an immediate reintubation because of laryngospasm. The ORE group showed lower heart rate (106.5 vs. 120.3 bpm; p < 0.001) and lower central venous pressure (10.4 vs. 11.4 mmHg; p = 0.001) than patients in the ICUE group within the first 24 h after FO, as well as higher systolic blood pressure within 7 h after operation (88.6 ± 2.5 vs. 85.6 ± 2.6 mmHg; p = 0.036). The ORE children manifested significantly less pleural effusions during 48 h after FO (38.0 vs. 49.5 ml/kg; p = 0.004), received less intravenous fluid administration within 24 h after FO (54.1 vs. 73.8 ml/kg; p = 0.019), less inotropic support (9.8 vs. 12.8 h of dopamine; p = 0.033), and less antibiotics (4.7 vs. 5.8 days; p = 0.037). ICUE children manifested metabolic acidosis more frequently than the ORE group 3-4 h after FO (p < 0.05). Immediate extubation after FO in comparison with extubation in the ICU appears to be associated with improved hemodynamics and reduced application of therapeutic interventions in the postoperative course.