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Angiopoietin-2 is a potential mediator of endothelial barrier dysfunction following cardiopulmonary bypass.

ABSTRACT: Endothelial activation leading to vascular barrier dysfunction and organ failure is a well-recognized complication of cardiovascular surgery with cardiopulmonary bypass (CPB). The endothelial-specific angiopoietin-Tie2 ligand-receptor system has been identified as a non-redundant regulator of endothelial activation. Binding of angiopoietin-2 (Ang-2) to the Tie2 receptor antagonizes Tie2 signaling and renders the endothelial barrier responsive to pro-inflammatory cytokines. We aimed to study the time course and potential triggering factors of Ang-2 release after CPB, as well as the association of Ang-2 changes with surrogates of increased vascular permeability, organ dysfunction, and outcome.Serum levels of Ang-2 from 25 adult patients (140 screened) were measured before and at 0, 12, and 24h following CPB procedure by in-house immuno-luminometric assay (ILMA), and compared with indices of organ dysfunction, duration of mechanical ventilation (MV), length of stay (LOS) in the intensive care unit (ICU), and hospital mortality. The effect of Ang-2 was studied in vitro by incubating high Ang-2 patient serum with endothelial cells (EC).Ang-2 levels steadily increased from 2.6 ± 2.4 ng/mL at 0 h up to 7.3 ± 4.6 ng/mL at 24h following CPB (P<0.001). The release of Ang-2 correlated with the duration of CPB, aortic cross-clamp time, and post-CPB lactate levels. Changes in Ang-2 during follow-up correlated with partial pressure of oxygen in arterial blood (PaO(2))/fraction of inspired oxygen (FiO(2)) ratio, alveolar-arterial oxygen tension difference (AaDO(2)), hemodynamics, fluid balance, and disease severity measures. Ang-2 levels at 12h predicted the duration of MV, ICU-LOS, and hospital mortality. High Ang-2 patient sera disrupted EC architecture in vitro, an effect reversed by treatment with the competitive Tie2 ligand angiopoietin-1 (Ang-1).Collectively, our results suggest that Ang-2 is a putative mediator of endothelial barrier dysfunction after CPB. These findings suggest that targeting the Ang/Tie2 pathway may mitigate organ dysfunction and improve outcome in patients undergoing CPB.

SUBMITTER: Clajus C

PROVIDER: S-EPMC4127984 | biostudies-literature | 2012 Nov

REPOSITORIES: biostudies-literature

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Angiopoietin-2 is a potential mediator of endothelial barrier dysfunction following cardiopulmonary bypass.

Clajus Christian C Lukasz Alexander A David Sascha S Hertel Barbara B Lichtinghagen Ralf R Parikh Samir M SM Simon André A Ismail Issam I Haller Hermann H Kümpers Philipp P

Cytokine 20120706 2

<h4>Introduction</h4>Endothelial activation leading to vascular barrier dysfunction and organ failure is a well-recognized complication of cardiovascular surgery with cardiopulmonary bypass (CPB). The endothelial-specific angiopoietin-Tie2 ligand-receptor system has been identified as a non-redundant regulator of endothelial activation. Binding of angiopoietin-2 (Ang-2) to the Tie2 receptor antagonizes Tie2 signaling and renders the endothelial barrier responsive to pro-inflammatory cytokines. W ...[more]

PMID: 22770562

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Project description:ObjectivesCardiopulmonary bypass-induced endothelial dysfunction has been inferred by changes in pulmonary vascular resistance, alterations in circulating biomarkers, and postoperative capillary leak. Endothelial-dependent vasomotor dysfunction of the systemic vasculature has never been quantified in this setting. The objective of the present study was to quantify acute effects of cardiopulmonary bypass on endothelial vasomotor control and attempt to correlate these effects with postoperative cytokines, tissue edema, and clinical outcomes in infants.DesignSingle-center prospective observational cohort pilot study.SettingPediatric cardiac ICU at a tertiary children's hospital.PatientsChildren less than 1 year old requiring cardiopulmonary bypass for repair of a congenital heart lesion.InterventionNone.Measurements and main resultsLaser Doppler perfusion monitoring was coupled with local iontophoresis of acetylcholine (endothelium-dependent vasodilator) or sodium nitroprusside (endothelium-independent vasodilator) to quantify endothelial-dependent vasomotor function in the cutaneous microcirculation. Measurements were obtained preoperatively, 2-4 hours, and 24 hours after separation from cardiopulmonary bypass. Fifteen patients completed all laser Doppler perfusion monitor (Perimed, Järfälla, Sweden) measurements. Comparing prebypass with 2-4 hours postbypass responses, there was a decrease in both peak perfusion (p = 0.0006) and area under the dose-response curve (p = 0.005) following acetylcholine, but no change in responses to sodium nitroprusside. Twenty-four hours after bypass responsiveness to acetylcholine improved, but typically remained depressed from baseline. Conserved endothelial function was associated with higher urine output during the first 48 postoperative hours (R = 0.43; p = 0.008).ConclusionsCutaneous endothelial dysfunction is present in infants immediately following cardiopulmonary bypass and recovers significantly in some patients within 24 hours postoperatively. Confirmation of an association between persistent endothelial-dependent vasomotor dysfunction and decreased urine output could have important clinical implications. Ongoing research will explore the pattern of endothelial-dependent vasomotor dysfunction after cardiopulmonary bypass and its relationship with biochemical markers of inflammation and clinical outcomes.

Project description:BackgroundEndothelial 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.MethodsClinical 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.ResultsA 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).ConclusionsCPB 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 registrationNTR4212 .

Project description:BackgroundMicrocirculatory perfusion disturbances are associated with increased morbidity and mortality in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). Technological advancements made it possible to monitor sublingual microcirculatory perfusion over time. The goal of this review is to provide an overview of the course of alterations in sublingual microcirculatory perfusion following CPB. The secondary goal is to identify which parameter of sublingual microcirculatory perfusion is most profoundly affected by CPB.MethodsPubMed and Embase databases were systematically searched according to PRISMA guidelines and as registered in PROSPERO. Studies that reported sublingual microcirculatory perfusion measurements before and after onset of CPB in adult patients undergoing cardiac surgery were included. The primary outcome was sublingual microcirculatory perfusion, represented by functional capillary density (FCD), perfused vessel density (PVD), total vessel density (TVD), proportion of perfused vessels (PPV), and microvascular flow index (MFI).ResultsThe search identified 277 studies, of which 19 fulfilled all eligibility criteria. Initiation of CPB had a profound effect on FCD, PVD, or PPV. Seventeen studies (89%) reported one or more of these parameters, and in 11 of those studies (65%), there was a significant decrease in these parameters during cardiac surgery; the other 6 studies (35%) reported no effect. In 29% of the studies, FCD, PVD, or PPV normalized by the end of cardiac surgery, and in 24% percent of the studies, this effect lasted at least 24?h. There was no clear effect of CPB on TVD and a mixed effect on MFI.ConclusionCPB during cardiac surgery impaired sublingual microcirculatory perfusion as reflected by reduced FCD, PVD, and PPV. Four studies reported this effect at least 24?h after surgery. Further research is warranted to conclude on the duration of CPB-induced microcirculatory perfusion disturbances and the relationship with clinical outcome.Trial registrationPROSPERO, CRD42019127798.

Project description:Cardiopulmonary bypass triggers systemic inflammation, resulting in lung injury, and frequently leads to prolonged mechanical ventilation. Biomarkers of systemic inflammation are required to predict the risk of such complications. We hypothesize that specific serum proteins can be used as biomarkers to predict the severity of lung injury following cardiac surgery.DesignRetrospective chart review study.SettingClinical variables were collected and used in conjuncture with unbiased proteomic analysis using mass spectrometry that was performed on frozen plasma samples from a study group (patients with mechanical ventilation > 48 hr post surgery) and a control group (patients with mechanical ventilation < 48 hr post surgery).SubjectsSubjects included were infants who underwent cardiac surgery with similar complexity (Society of Thoracic Surgeons-European Association for Cardiothoracic Surgery 3 or 4) using cardiopulmonary bypass. Patients in both groups were matched for their weight, age, and duration of cardiopulmonary bypass.InterventionNone.Measurements and main resultsFour-hundred eighty-three proteins were identified (99% minimum confidence and two peptides minimum, protein false discovery rate 0.1%) on proteomic analysis of four control and four study patients at precardiopulmonary bypass, 0, and 48 hours postcardiopulmonary bypass samples. Thirty-six of 178 proteins were significantly different (≥ 1.5-fold; p < 0.05) at precardiopulmonary bypass (top increased: tenascin; top decreased: tetranectin), 18 of 140 proteins at 0 hour (top increased: hemoglobin beta; top decreased: C8 beta), and 25 of 166 proteins at 48 hours post surgery (top increased: proteoglycan 4; top decreased: galectin-3-binding protein). The top pathway involved cytoskeleton remodeling. Other pathways involved immune response and blood coagulation. Proteoglycan 4 was validated by enzyme-linked immunosorbent assay in a different set of samples (n = 20/group; mean ± sd: 128 ± 67 vs 195 ± 160 ng/mL) (p = 0.037).ConclusionsMultiple proteomic biomarkers were associated with worse respiratory outcomes. Precardiopulmonary bypass biomarkers might indicate risk factors (e.g., abnormalities of coagulation), whereas those identified at 0 hour and post cardiopulmonary bypass may reflect mechanisms of ongoing pathobiology.

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Angiopoietin-2 is a potential mediator of endothelial barrier dysfunction following cardiopulmonary bypass.

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Angiopoietin-2 is a potential mediator of endothelial barrier dysfunction following cardiopulmonary bypass.

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