Endothelial permeability following coronary artery bypass grafting: an observational study on the possible role of angiopoietin imbalance

Impact of Pulse Pressure on Acute Brain Injury in Venoarterial ECMO Patients with Cardiogenic Shock During the First 24 Hours of ECMO Cannulation: Analysis of the Extracorporeal Life Support Organization Registry

Background : Low pulse pressure (PP) in venoarterial-extracorporeal membrane oxygenation (VA-ECMO) is a marker of cardiac dysfunction and has been associated with acute brain injury (ABI) as continuous-flow centrifugal pump may lead to endothelial dysregulation. Methods : We retrospectively analyzed adults (≥18 years) on "peripheral" VA-ECMO support for cardiogenic shock in the Extracorporeal Life Support Organization Registry (1/2018-7/2023). Cubic splines were used to establish a threshold (PP≤10 mmHg at 24 hours of ECMO support) for "early low" PP. ABI included central nervous system (CNS) ischemia, intracranial hemorrhage, brain death, and seizures. Multivariable logistic regressions were performed to examine whether PP≤10 mmHg was associated with ABI. Covariates included age, sex, body mass index, pre-ECMO variables (temporary mechanical support, vasopressors, cardiac arrest), on-ECMO variables (pH, PaO 2 , PaCO 2 ), and on-ECMO complications (hemolysis, arrhythmia, renal replacement therapy). Results : Of 9,807 peripheral VA-ECMO patients (median age=57.4 years, 67% male), 8,294 (85%) had PP>10 mmHg vs. 1,513 (15%) had PP≤10 mmHg. Patients with PP≤10 mmHg experienced ABI more frequently vs. PP>10 mmHg (15% vs. 11%, p<0.001). After adjustment, PP≤10 mmHg was independently associated with ABI (adjusted odds ratio [aOR]=1.25, 95% confidence interval [CI]=1.06-1.48, p=0.01). CNS ischemia and brain death were more common in patients with PP≤10 mmHg vs. PP>10 mmHg (8% vs. 6%, p=0.008; 3% vs. 1%, p<0.001). PP≤10 mmHg was associated with CNS ischemia (aOR=1.26, 95%CI=1.02-1.56, p=0.03) but not intracranial hemorrhage (aOR=1.14, 95%CI=0.85-1.54, p=0.38). Conclusions : Early low PP (≤10 mmHg) at 24 hours of ECMO support was associated with ABI, particularly CNS ischemia, in peripheral VA-ECMO patients.

The association of body composition assessment with hospital length of stay in off-pump coronary artery bypass patients

Introduction

Bioelectrical impedance analysis is a widely available, non-invasive method for body composition assessment.

Aim

To elucidate the perioperative body composition alterations and their prognostic utility for hospital length of stay (LOS) in low risk, off-pump coronary artery bypass (OPCAB) patients.

Material and methods

Fifty patients undergoing elective OPCAB were included in the study. Body composition assessments were performed 1 day before the scheduled surgery and on the 6th postoperative day. Patients were grouped into < 9 days (n = 29, 58%) and ≥ 9 days (n = 21, 42%). Multivariate logistic regression analysis was performed to create a body composition-based screening panel for prolonged hospital stay.

Results

No significant differences in anthropometric measurements, clinical characteristics or occurrence of postoperative complications were detected between the study groups. Patients with longer hospitalization had significantly higher content of fat mass (FM%) and fat mass index (FMI), and significantly lower content of fat free mass (FFM%) baseline parameters (p = 0.011, p = 0.04 and p = 0.012, respectively). High FM% values had 15-fold, low FFM% values had 13-fold and high FMI values had 7-fold higher risk of experiencing longer stay in the hospital (p = 0.001, p = 0.001 and p = 0.005, respectively). The combined panel of three variables (higher FM%, lower FFM% and higher FMI) had 16-fold higher risk of longer hospitalization (adjusted OR = 16.40; 95% CI: 3.52-76.34; p = 0.0004).

Conclusions

Preoperative high FM and low FFM content are independent predictors of prolonged hospital length of stay in normal- and increased-BMI patients after OPCAB.

Angiopoietin-2 is associated with capillary leak and predicts complications after cardiac surgery

BACKGROUND

Patients undergoing cardiac surgery are prone to numerous complications. Increased vascular permeability may be associated with morbidity and mortality due to hemodynamic instability, fluid overload, and edema formation. We hypothesized that markers of endothelial injury and inflammation are associated with capillary leak, ultimately increasing the risk of postoperative complications.

METHODS

In this prospective, observational, multidisciplinary cohort study at our tertiary academic medical center, we recruited 405 cardiac surgery patients. Patients were assessed daily using body impedance electrical analysis, ultrasound, sublingual intravital microscopy, and analysis of serum biomarkers. Multivariable models, as well as machine learning, were used to study the association of angiopoietin-2 with extracellular water as well as common complications after cardiac surgery.

RESULTS

The majority of patients underwent coronary artery bypass grafting, valvular, or aortic surgeries. Across the groups, extracellular water increased postoperatively (20 ± 6 preoperatively to 29 ± 7L on postoperative day 2; P < 0.001). Concomitantly, the levels of the biomarker angiopoietin-2 rose, showing a strong correlation based on the time points of measurements (r = 0.959, P = 0.041). Inflammatory (IL-6, IL-8, CRP) and endothelial biomarkers (VE-Cadherin, syndecan-1, ICAM-1) suggestive of capillary leak were increased. After controlling for common risk factors of edema formation, we found that an increase of 1 ng/mL in angiopoietin-2 was associated with a 0.24L increase in extracellular water (P < 0.001). Angiopoietin-2 showed increased odds for the development of acute kidney injury (OR 1.095 [95% CI 1.032, 1.169]; P = 0.004) and was furthermore associated with delayed extubation, longer time in the ICU, and a higher chance of prolonged dependence on vasoactive medication. Machine learning predicted postoperative complications when capillary leak was added to standard risk factors.

CONCLUSIONS

Capillary leak and subsequent edema formation are relevant problems after cardiac surgery. Levels of angiopoietin-2 in combination with extracellular water show promising potential to predict postoperative complications after cardiac surgery.

TRIAL REGISTRATION NUMBER

German Clinical Trials Registry (DRKS No. 00017057), Date of registration 05/04/2019, www.drks.de.

Endothelial Dysfunction in Patients Undergoing Cardiac Surgery: A Narrative Review and Clinical Implications

Cardiac surgery is one of the highest-risk procedures, usually involving cardiopulmonary bypass and commonly inducing endothelial injury that contributes to the development of perioperative and postoperative organ dysfunction. Substantial scientific efforts are being made to unravel the complex interaction of biomolecules involved in endothelial dysfunction to find new therapeutic targets and biomarkers and to develop therapeutic strategies to protect and restore the endothelium. This review highlights the current state-of-the-art knowledge on the structure and function of the endothelial glycocalyx and mechanisms of endothelial glycocalyx shedding in cardiac surgery. Particular emphasis is placed on potential strategies to protect and restore the endothelial glycocalyx in cardiac surgery. In addition, we have summarized and elaborated the latest evidence on conventional and potential biomarkers of endothelial dysfunction to provide a comprehensive synthesis of crucial mechanisms of endothelial dysfunction in patients undergoing cardiac surgery, and to highlight their clinical implications.

Microvascular dysfunction following cardiopulmonary bypass plays a central role in postoperative organ dysfunction

Despite significant advances in surgical technique and strategies for tissue/organ protection, cardiac surgery involving cardiopulmonary bypass is a profound stressor on the human body and is associated with numerous intraoperative and postoperative collateral effects across different tissues and organ systems. Of note, cardiopulmonary bypass has been shown to induce significant alterations in microvascular reactivity. This involves altered myogenic tone, altered microvascular responsiveness to many endogenous vasoactive agonists, and generalized endothelial dysfunction across multiple vascular beds. This review begins with a survey of in vitro studies that examine the cellular mechanisms of microvascular dysfunction following cardiac surgery involving cardiopulmonary bypass, with a focus on endothelial activation, weakened barrier integrity, altered cell surface receptor expression, and changes in the balance between vasoconstrictive and vasodilatory mediators. Microvascular dysfunction in turn influences postoperative organ dysfunction in complex, poorly understood ways. Hence the second part of this review will highlight in vivo studies examining the effects of cardiac surgery on critical organ systems, notably the heart, brain, renal system, and skin/peripheral tissue vasculature. Clinical implications and possible areas for intervention will be discussed throughout the review.

Endothelial Damage and Muscle Wasting in Cardiac Surgery Patients

This is a post-hoc analysis to assess the effect of anesthesia, surgical trauma, and extracorporeal circuit on endothelial integrity, microvascular permeability, and extracellular fluid balance, as well as on skeletal muscle catabolism, in patients undergoing elective cardiac surgery. We included 127 well-nourished patients undergoing “on-pump” elective cardiac surgery. One day prior to surgery (D0) and again on postoperative day 7 (POD7), body mass index, body composition assessment, hand-grip strength (HGS), and mid-upper arm muscle circumference (MAMC) were measured. Patients were assigned to early recovery (ER) and late recovery (LR) groups, depending on the duration of ICU stay (cut-off 48 hours). The magnitude of change (Δ) in all parameters studied was assessed in ER versus LR groups, regarding (i) epithelial tissue dysfunction (Δ-Extra-Cellular Water percentage (Δ-ECW%), Δ-Phase Angle (Δ-PhA)), (ii) skeletal muscle mass catabolism (Δ-Skeletal muscle mass reduction%, Δ-Hand Grip Strength (Δ-HGS) and Δ-Mid Upper-Arm Muscle Circumference (Δ-MAMC)). Baseline measurements were similar in both groups. A significant difference was observed in all Δ-parameters studied (Δ-ECW%, Δ-PhA and muscle catabolism, Δ-HGS, Δ-MAMC), the worse results being correlated to the LR group. The results raise the issue that patients with early recovery may silently have pathological conditions, continuing even on the day of discharge - further research should be planned.

Plasma from patients undergoing coronary artery bypass graft surgery does not activate endothelial cells under shear stress in vitro

Background:

Cardiac surgery with cardiopulmonary bypass (CPB) is commonly associated with acute kidney injury, and microvascular endothelial inflammation is a potential underlying mechanism. We hypothesized that pro-inflammatory components of plasma from patients who underwent coronary artery bypass graft surgery with CPB induce endothelial adhesion molecule expression when incorporating altered shear stress in the in vitro model.

Methods:

The clinical characteristics and markers of systemic inflammation and kidney injury were analyzed pre and postoperatively in 29 patients undergoing coronary artery bypass grafting with CPB. The effects of tumor necrosis factor (TNF)-α and patient plasma on the expression of endothelial inflammation and adhesion markers were analyzed in vitro.

Results:

Plasma TNF-α was elevated 6 h postoperation (median: 7.3 pg/ml (range: 2.5–94.8 pg/ml)). Neutrophil gelatinase-associated lipocalin in plasma peaked 6 h (99.8 ng/ml (52.6–359.1 ng/ml)) and in urine 24 h postoperation (1.6 ng/mg (0.2–6.4 ng/mg)). Urinary kidney injury molecule-1 concentration peaked 24 h postoperation (0.5 ng/mg (0.2–1.2 ng/mg). In vitro, the expression of E-selectin was induced by 20 pg/ml TNF-α. In addition, the expression of interleukin-8, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 was induced by 100 pg/ml TNF-α. Compared to healthy control plasma exposure, postoperative plasma did not increase the expression of markers of endothelial inflammation and adhesion under shear stress in vitro.

Conclusion:

Patients undergoing CPB surgery showed mild systemic inflammation and kidney injury. However, the plasma components did not stimulate endothelial inflammation and adhesion molecule expression in vitro.

Perioperative Vascular Biomarker Profiling in Elective Surgery Patients Developing Postoperative Delirium: A Prospective Cohort Study

Background: Postoperative delirium (POD) ranks among the most common complications in surgical patients. Blood-based biomarkers might help identify the patient at risk. This study aimed to assess how serum biomarkers with specificity for vascular and endothelial function and for inflammation are altered, prior to or following surgery in patients who subsequently develop POD. Methods: This was a study on a subcohort of consecutively recruited elective non-cardiac as well as cardiac surgery patients (age > 60 years) of the single-center PROPDESC trial at a German tertiary care hospital. Serum was sampled prior to and following surgery, and the samples were subjected to bead-based multiplex analysis of 17 serum proteins (IL-3, IL-8, IL-10, Cripto, CCL2, RAGE, Resistin, ANGPT2, TIE2, Thrombomodulin, Syndecan-1, E-Selectin, VCAM-1, ICAM-1, CXCL5, NSE, and uPAR). Development of POD was assessed during the first five days after surgery, using the Confusion Assessment Method for ICU (CAM-ICU), the CAM, the 4-‘A’s test (4AT), and the Delirium Observation Scale (DOS). Patients were considered positive if POD was detected at least once during the visitation period by any of the applied methods. Non-parametric testing, as well as propensity score matching were used for statistical analysis. Results: A total of 118 patients were included in the final analysis; 69% underwent non-cardiac surgery, median overall patient age was 71 years, and 59% of patients were male. In the whole cohort, incidence of POD was 28%. The male gender was significantly associated with the development of POD (p = 0.0004), as well as a higher ASA status III (p = 0.04). Incidence of POD was furthermore significantly increased in cardiac surgery patients (p = 0.002). Surgery induced highly significant changes in serum levels of almost all biomarkers except uPAR. In preoperative serum samples, none of the analyzed parameters was significantly altered in subsequent POD patients. In postoperative samples, CCL2 was significantly increased by a factor of 1.75 in POD patients (p = 0.03), as compared to the no-POD cohort. Following propensity score matching, CCL2 remained the only biomarker that showed significant differences in postoperative values (p = 0.01). In cardiac surgery patients, postoperative CCL2 serum levels were more than 3.5 times higher than those following non-cardiac surgery (p < 0.0001). Moreover, after cardiac surgery, Syndecan-1 serum levels were significantly increased in POD patients, as compared to no-POD cardiac surgery patients (p = 0.04). Conclusions: In a mixed cohort of elective non-cardiac as well as cardiac surgery patients, preoperative serum biomarker profiling with specificity for vascular dysfunction and for systemic inflammation was not indicative of subsequent POD development. Surgery-induced systemic inflammation—as evidenced by the significant increase in CCL2 release—was associated with POD, particularly following cardiac surgery. In those patients, postoperative glycocalyx injury might furthermore contribute to POD development.

Changes in Plasma Angiopoietin Levels After Transcatheter Aortic Valve Replacement and Surgical Aortic Valve Replacement: A Prospective Cohort Study

OBJECTIVE

Angiopoietins (Angs) regulate endothelial permeability. Ang-1 and 2 (Ang-1 and Ang-2) are implied in endothelial stability through an antagonism effect. The objectives of the present study were to describe and compare changes in Ang levels after transcatheter aortic valve replacement (TAVR) and surgical aortic valve replacement (SAVR).

DESIGN

A prospective, single-center study.

PARTICIPANTS

Adult patients with aortic stenosis scheduled for SAVR or TAVR.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Ang-1 and Ang-2 were measured using an enzyme-linked immunosorbent assay right before surgery (T0), at the end of surgery (T1), and at day one (T2). Sixty consecutive patients (SAVR group [n = 30] and TAVR group [n = 30]) were included between January and June 2017. Ang-1 decreased significantly after both TAVR (T0: 3,663 [2,602-4,262]; T1: 1,611 [981-2,409]; T2: 1,082 [652-1,589] ng/mL; p < 0.0001) and SAVR (T0: 1,603 [975-2,849]; T1: 783 [547-1,024]; T2: 828 [460-1,227] ng/mL; p = 0.0001). Ang-2 increased significantly after SAVR (T0: 2,472 [1,502-3,622]; T1: 2,997 [1,759-3,839]; T2: 5,421 [3,557-7,087] ng/mL; p < 0.0001) but did not change markedly after TAVR (T0: 3,343 [2,661-6,272]; T1: 3,788 [2,574-5,016]; T2: 3,446 [3,029-6,313] ng/mL; p = 0.066). Among patients with paravalvular leakage, the changes in the plasma Ang-2 level and the Ang-2/Ang-1 ratio were greater.

CONCLUSION

SAVR induces greater alterations of Ang homeostasis than TAVR, confirming a role for the use of cardiopulmonary bypass. Paravalvular leakage after TAVR is associated with Ang changes similar to those observed with SAVR.

Gene expression in the Angiopoietin/TIE axis is altered in peripheral tissue of ovarian cancer patients: A prospective observational study

AIMS

Clinical studies suggest altered systemic vascular biology in cancer patients. We assessed expression patterns of endothelial activation- and vascular leakage-related genes in tumor as well as in tumor-free peripheral tissues from patients with and without ovarian cancer (OC).

MAIN METHODS

Patients being scheduled for laparotomy for either gynecologic benign diagnosis (n = 10) or for advanced-stage OC (n = 22) were prospectively recruited to this observational study. Serum samples were taken preoperatively, and tissue samples were taken from peripheral abdominal wall musculature, tumor-free peritoneum and the tumor itself.

KEY FINDINGS

Patients in OC group received significantly more fluid per time intraoperatively (p = 0.01). IL-8 and MCP-1/CCL2, VCAM-1 (CD 106) and ICAM-1 (CD 54) as well as Thrombomodulin were significantly increased in cancer patients' serum at baseline (p = 0.03). Expression of distinct vascular leakage-related genes (Angiopoietin-1 (ANG-1), ANG-2, TIE2, VEGFR1, VEGFR2) was significantly altered in tumor tissue of OC patients (p = 0.003), while in tumor-free peritoneal tissue, ANG-2/1 expression ratio was more than doubled in OC group (p = 0.03). In peripheral musculature, particularly genes from the ANG/TIE axis were significantly changed in OC patients (p = 0.005), suggesting a distinct vascular leakage-related genotype. Gene expression changes in OC patients were significantly associated with the postoperative fluid balance (p = 0.03).

SIGNIFICANCE

Altered expression of barrier dysfunction- and angiogenesis-associated genes from the ANG/TIE axis was detected not only in tumor but also in peripheral tissues of cancer patients. This may contribute to a systemic vascular leakage-related genotype.

Low-body-perfusion via an arterial sheath reduces inflammation after aortic arch reconstruction surgery

Pediatric cardiac surgeries involving aortic arch reconstruction are complex and require long cardiopulmonary bypass (CPB) times with deep hypothermic circulatory arrest (DHCA). Selective perfusion techniques have been developed to prevent the deleterious consequences of DHCA associated hypoperfusion. The effectivity of low body perfusion through cannulation of the femoral artery with an arterial sheath remains to be elucidated. We compared perfusion and inflammation in patients receiving selective antegrade cerebral perfusion (ACP) only to low body perfusion (LBP) in addition to ACP during DHCA for aortic arch reconstruction surgery. There was no difference in patient characteristics, cardiac pathologies, or performed procedures between ACP and LBP groups. Lactate levels increased after cardiac arrest in both groups. However, lactate levels were lower after 1 h reperfusion, at the end of extracorporeal circulation (ECC), and after surgery in LBP group compared to ACP only. Furthermore, creatinine was increased in ACP group on postoperative day 1 compared to LBP group but no acute kidney injury was observed in any group. IL-6 concentration increased in ACP group, while remained unchanged in LBP group compared to pre surgical values and were significantly lower compared to ACP group on postoperative days 1 and 2. LBP via an arterial sheath during cardiac arrest for aortic arch reconstruction surgery in addition to ACP, improves post ECC tissue perfusion as indicated by lower lactate levels and reduces creatinine levels suggesting milder kidney injury. LBP seems to prevent postoperative inflammation through a reduction in procedural duration or enhanced perfusion and thereby improves the outcome after aortic arch reconstruction surgery.

Altered kinetics of circulating progenitor cells in cardiopulmonary bypass (CPB) associated vasoplegic patients: A pilot study

Vasoplegia observed post cardiopulmonary bypass (CPB) is associated with substantial morbidity, multiple organ failure and mortality. Circulating counts of hematopoietic stem cells (HSCs) and endothelial progenitor cells (EPC) are potential markers of neo-vascularization and vascular repair. However, the significance of changes in the circulating levels of these progenitors in perioperative CPB, and their association with post-CPB vasoplegia, are currently unexplored. We enumerated HSC and EPC counts, via flow cytometry, at different time-points during CPB in 19 individuals who underwent elective cardiac surgery. These 19 individuals were categorized into two groups based on severity of post-operative vasoplegia, a clinically insignificant vasoplegic Group 1 (G1) and a clinically significant vasoplegic Group 2 (G2). Differential changes in progenitor cell counts during different stages of surgery were compared across these two groups. Machine-learning classifiers (logistic regression and gradient boosting) were employed to determine if differential changes in progenitor counts could aid the classification of individuals into these groups. Enumerating progenitor cells revealed an early and significant increase in the circulating counts of CD34+ and CD34+CD133+ hematopoietic stem cells (HSC) in G1 individuals, while these counts were attenuated in G2 individuals. Additionally, EPCs (CD34+VEGFR2+) were lower in G2 individuals compared to G1. Gradient boosting outperformed logistic regression in assessing the vasoplegia grouping based on the fold change in circulating CD 34+ levels. Our findings indicate that a lack of early response of CD34+ cells and CD34+CD133+ HSCs might serve as an early marker for development of clinically significant vasoplegia after CPB.

Dynamic changes of angiopoietins and endothelial nitric oxide supply during fluid resuscitation for major gyn-oncological surgery: a prospective observation

BACKGROUND

Despite goal-directed hemodynamic therapy, vascular function may deteriorate during surgery for advanced abdominal tumor masses. Fluid administration has been shown to be associated with distinct changes in serum levels of functional proteins. We sought to determine how serum total protein and angiopoietin (ANG) levels change during major abdominal tumor surgery. In addition, ex vivo endothelial nitric oxide synthase (eNOS) activation as well as NO bioavailability in vivo were assessed.

METHODS

30 patients scheduled for laparotomy for late-stage ovarian or uterine cancer were prospectively included. Advanced hemodynamic monitoring as well as protocol-driven goal-directed fluid optimization were performed. Total serum protein, ANG-1, -2, and soluble TIE2 were determined pre-, intra-, and postoperatively. Phosphorylation of eNOS was assessed in microvascular endothelial cells after incubation with patient serum, and microvascular reactivity was determined in vivo by near-infrared spectroscopy and arterial vascular occlusion.

RESULTS

Cardiac output as well as preload gradually decreased during surgery and were associated with a median total fluid intake of 12.8 (9.7-15.4) mL/kg*h and a postoperative fluid balance of 6710 (4113-9271) mL. Total serum protein decreased significantly from baseline (66.5 (56.4-73.3) mg/mL) by almost half intraoperatively (42.7 (36.8-51.5) mg/mL, p < 0.0001) and remained at low level. While ANG-1 showed no significant dilutional change (baseline: 12.7 (11.9-13.9) ng/mL, postop.: 11.6 (10.8 -13.5) ng/mL, p = 0.06), serum levels of ANG-2 were even increased postoperatively (baseline: 2.2 (1.6-2.6) ng/mL vs. postop.: 3.4 (2.3-3.8) ng/mL, p < 0.0001), resulting in a significant shift in ANG-2 to ANG-1 ratio. Ex vivo phosphorylation of eNOS was decreased depending on increased ANG-2 levels and ANG-2/1 ratio (Spearman r = - 0.37, p = 0.007). In vivo, increased ANG-2 levels were associated with impaired capillary recruitment and NO bioavailability (Spearman r = - 0.83, p = 0.01).

CONCLUSIONS

Fluid resuscitation-associated changes in serum vascular mediator profile during abdominal tumor surgery were accompanied by impaired eNOS activity ex vivo as well as reduced NO bioavailability in vivo. Our results may explain disturbed microvascular function in major surgery despite goal-directed hemodynamic optimization.

Network of Mediators for Vascular Inflammation and Leakage Is Dysbalanced during Cytoreductive Surgery for Late-Stage Ovarian Cancer

Background

Cytoreductive surgery (CS) in late-stage ovarian cancer patients is often challenging due to extensive volume shifts, and high fluid intake may provoke postoperative complications. Expression of vasoactive mediators is altered in cancer patients, which may affect systemic vascular function. We sought to assess how serum levels of vasoactive markers and mediators change during CS in ovarian cancer.

Methods

Following IRB approval and informed consent, pre- and postoperative serum samples were analyzed in 26 late-stage ovarian cancer patients using multiplex protein arrays and ELISA.

Results

The proinflammatory cytokines and chemokines IL-6, IL-8, and CCL2 were significantly elevated after 24 hrs compared to the baseline values, with IL-6 and IL-8 being most prominently increased. While ANGPT1 remained unchanged after surgery, its competitive antagonist ANGPT2 was significantly increased. In contrast, serum levels of the ANGPT receptor TIE2 were decreased to 0.6 of the baseline values. While VEGF-D, E-selectin, P-selectin, ICAM-1, and PECAM-1 remained unchanged, serum activity of both thrombomodulin and syndecan-1 was significantly increased following surgery.

Conclusion

We identified a regulatory network of acute-phase reaction during CS in late-stage ovarian cancer. This suggests that IL-6 exerts positive regulation of other proinflammatory mediators and, by upregulating ANGPT2 and suppressing ANGPT1, induces a serum profile that promotes vascular leakage. This may contribute to the observed hemodynamic alterations during CS procedures.

Targeted transcriptional profiling of the tumor microenvironment reveals lymphocyte exclusion and vascular dysfunction in metastatic osteosarcoma

Osteosarcoma (OS) is the most common bone tumor in pediatric and adolescent/young adult patients yet little is known about the microenvironment that supports this aggressive disease. We have used targeted gene expression profiling and immunohistochemistry to characterize the microenvironment of metastatic and non-metastatic OS specimens from pediatric patients exhibiting poor histologic response to chemotherapy. Our results indicate that metastatic specimens exhibit lymphocyte exclusion as T cells are confined to the periphery of the pulmonary lesions. Furthermore, our data provides evidence of vascular dysfunction in metastatic OS indicated by increased expression of VEGFA, an increased ANGPT2:ANGPT1 gene expression ratio, and decreased expression of SELE, the gene encoding the adhesion molecule E-selectin. Moreover, correlation analyses show an inverse relationship between lymphocyte abundance and markers of vascular dysfunction exclusively in the metastatic specimens. Together, our data shows that the non-metastatic OS specimens demonstrate increased expression of various immunotherapeutic targets in comparison metastatic specimens and identifies vascular dysfunction and lymphocyte exclusion as important processes for therapeutic intervention in metastatic disease.

Microcirculatory perfusion disturbances following cardiac surgery with cardiopulmonary bypass are associated with in vitro endothelial hyperpermeability and increased angiopoietin-2 levels

Background

Endothelial hyperpermeability following cardiopulmonary bypass (CPB) contributes to microcirculatory perfusion disturbances and postoperative complications after cardiac surgery. We investigated the postoperative course of renal and pulmonary endothelial barrier function and the association with microcirculatory perfusion and angiopoietin-2 levels in patients after CPB.

Methods

Clinical data, sublingual microcirculatory data, and plasma samples were collected from patients undergoing coronary artery bypass graft surgery with CPB (n = 17) before and at several time points up to 72 h after CPB. Renal and pulmonary microvascular endothelial cells were incubated with patient plasma, and in vitro endothelial barrier function was assessed using electric cell–substrate impedance sensing. Plasma levels of angiopoietin-1,-2, and soluble Tie2 were measured, and the association with in vitro endothelial barrier function and in vivo microcirculatory perfusion was determined.

Results

A plasma-induced reduction of renal and pulmonary endothelial barrier function was observed in all samples taken within the first three postoperative days (P < 0.001 for all time points vs. pre-CPB). Angiopoietin-2 and soluble Tie2 levels increased within 72 h after CPB (5.7 ± 4.4 vs. 1.7 ± 0.4 ng/ml, P < 0.0001; 16.3 ± 4.7 vs. 11.9 ± 1.9 ng/ml, P = 0.018, vs. pre-CPB), whereas angiopoietin-1 remained stable. Interestingly, reduced in vitro renal and pulmonary endothelial barrier moderately correlated with reduced in vivo microcirculatory perfusion after CPB (r = 0.47, P = 0.005; r = 0.79, P < 0.001). In addition, increased angiopoietin-2 levels moderately correlated with reduced in vitro renal and pulmonary endothelial barrier (r = − 0.46, P < 0.001; r = − 0.40, P = 0.005) and reduced in vivo microcirculatory perfusion (r = − 0.43, P = 0.01; r = − 0.41, P = 0.03).

Conclusions

CPB is associated with an impairment of in vitro endothelial barrier function that continues in the first postoperative days and correlates with reduced postoperative microcirculatory perfusion and increased circulating angiopoietin-2 levels. These results suggest that angiopoietin-2 is a biomarker for postoperative endothelial hyperpermeability, which may contribute to delayed recovery of microcirculatory perfusion after CPB.

Trial registration

NTR4212.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2418-5) contains supplementary material, which is available to authorized users.

Experimental murine acute lung injury induces increase of pulmonary TIE2-expressing macrophages

Background

Breakdown of the alveolo-capillary wall is pathognomonic for Acute Lung Injury (ALI). Angiopoietins, vascular-specific growth factors, are linked to endothelial barrier dysfunction, and elevated Angiopoietin-2 (ANG2) levels are associated with poor outcome of ALI patients. Specialized immune cells, referred to as ‘TIE2-expressing monocytes and macrophages’ (TEM), were shown to specifically respond to ANG2 binding. However, their involvement in acute inflammatory processes is so far completely undescribed. Thus, our aim was to assess the dynamics of TEMs in a murine model of ALI.

Results

Intratracheal instillation of LPS induced a robust pulmonary pro-inflammatory response with endothelial barrier dysfunction and significantly enhanced ANG2 expression. The percentage number of TEMs, assessed by FACS analysis, was more than trebled compared to controls, with TEM count in lungs reaching more than 40% of all macrophages. Such distinct dynamic was absent in all other analyzed compartments (alveolar space, spleen, blood). Incubation of the monocytic cell line THP-1 with LPS or TNF-α resulted in a dose-dependent, significant upregulation of TIE2, suggesting that not recruitment from extra-pulmonary compartments but TIE2 upregulation in resident macrophages accounts for increased lung TEM frequencies.

Conclusions

For the first time, our data provide evidence that the activity of TEMs changes at sites of acute inflammation.

Electronic supplementary material

The online version of this article (10.1186/s12950-018-0188-5) contains supplementary material, which is available to authorized users.

Vascular Endothelial Dysfunction during Cardiac Surgery: On-Pump versus Off-Pump Coronary Surgery

BACKGROUND

Cardiac surgery often causes ischemia and development of a systemic inflammatory response syndrome, which impairs vascular barrier function, normally maintained by the endothelial cell line and the endothelial glycocalyx (EG). The EG normally covers and protects healthy endothelial cells throughout the vasculature. The aim of the present study was to assess the disruption of the cellular part of the microvascular barrier by determining parameters of endothelial cell activation known to influence and reflect cell-cell junctional integrity. Particular attention was placed on angiopoietins and their important effects on endothelial gap junctions. Furthermore, comparative measurements were undertaken in patients undergoing on- and off-pump cardiac surgery, the latter group presumably experiencing less ischemic stress.

METHODS

30 patients undergoing elective coronary artery bypass surgery were assigned to the conventional coronary artery bypass (CCAB) group (n = 15) or the off-pump coronary artery bypass grafting (OPCAB) group (n = 15). Blood samples were obtained for measuring angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), vascular endothelial (VE)-cadherin, and endocan at various time points.

RESULTS

There were significant increases in all measured parameters in both study groups versus the respective basal values. Maximal increases were as follows: Ang-1: CCAB +220%, OPCAB +166%, p < 0.05 each; Ang-2: CCAB +150%, OPCAB +20%, p < 0.05 each; VE-cadherin: CCAB +87%, OPCAB +66%, p < 0.05 each; endocan: CCAB +323%, OPCAB +72%, p < 0.05 each.

CONCLUSION

The present study demonstrates the activation of endothelial cells, shedding of cell-cell contacts and a potential intrinsic counterregulation by Ang-1 and endocan in patients undergoing major cardiac surgery. Quantitatively greater deviations of parameters in the CCAB than in the OPCAB group suggest a relation between the occurrence of ischemia/reperfusion and the extent of endothelial activation.

Pulmonary vascular inflammation: effect of TLR signalling on angiopoietin/TIE regulation

Increased pulmonary vascular resistance is a critical complication in sepsis. Toll-like receptor (TLR) as well as angiopoietin (ANG) signalling both contribute to the emergence of pulmonary arterial hypertension. We hypothesized that TLR stimulation by bacterial ligands directly affects expression and secretion of ligands and receptors of the angiopoietin/TIE axis. Microvascular endothelial (HPMEC) and smooth muscle cells (SMC) of pulmonary origin were incubated with thrombin and with ligands for TLR2, -4, -5, and -9. Expression and secretion of ANG1, -2, TIE2 and IL-8 were determined using quantitative real-time PCR and ELISA. TLR stimulation had no impact either on the expression of ANG2 and TIE2 in HPMEC or on that of ANG1 in SMC. However, overall levels of both released ANG1 and -2 were halved upon stimulation with the TLR9 ligand CpG, and ANG2 release was significantly enhanced by TLR4 activation when initially provoked by sequentially performed stimulation. Furthermore, enhanced ANG2 activity increased endothelial permeability, as demonstrated in an in vitro transwell assay. We conclude that sole TLR stimulation by bacterial ligands plays no significant role for altered expression and secretion of ANG1, -2 and TIE2 in human pulmonary vascular cells. The interplay between various stimuli is required to induce imbalances between ANG1 and -2.

Systemic angiopoietin-1/2 dysregulation following cardiopulmonary bypass in adults

AIM

Vascular leakage following cardiopulmonary bypass contributes to morbidity. Angiopoietin-1 and -2 are biomarkers of endothelial dysfunction. Our aim was to characterize Ang-1 and -2 association with clinical characteristics and outcomes.

METHODS

Observational cohort study measuring Ang-1/-2 with a panel of cytokines in adults undergoing cardiopulmonary bypass.

RESULTS

Ang-2 levels increased immediately postop whereas Ang-1 levels decreased over time. No significant correlation was found with other inflammatory mediators. High correlation was found between the hospital length of stay and Ang-2 increase at 24 h (rho = 0.590; p < 0.0001). The predictors of Ang-2 increase were female gender, cross clamp time, transfusion of blood and absence of angiotensin-converting enzyme inhibitor as a pre-op medication.

CONCLUSION

Angiopoietins can detect vascular leakage early and could impact patient's management to decrease length of stay after cardiac surgery.