Glycocalyx Damage Research Articles

Choice of Fluid Therapy in the Initial Management of Sepsis, Severe Sepsis, and Septic Shock.

Sepsis results in disruption of the endothelial glycocalyx layer and damage to the microvasculature, resulting in interstitial accumulation of fluid and subsequently edema. Fluid resuscitation is a mainstay in the initial treatment of sepsis, but the choice of fluid is unclear. The ideal resuscitative fluid is one that restores intravascular volume while minimizing edema; unfortunately, edema and edema-related complications are common consequences of current resuscitation strategies. Crystalloids are recommended as first-line therapy, but the type of crystalloid is not specified. There is increasing evidence that normal saline is associated with increased mortality and kidney injury; balanced crystalloids may be a safer alternative. Albumin is similar to crystalloids in terms of outcomes in the septic population but is costlier. Hydroxyethyl starches appear to increase mortality and kidney injury in the critically ill and are no longer indicated in these patients. In the trauma population, the shift to plasma-based resuscitation with decreased use of crystalloid and colloid in the treatment of hemorrhagic shock has led to decreased inflammatory and edema-mediated complications. Studies are needed to determine if these benefits also occur with a similar resuscitation strategy in the setting of sepsis.

Syndecan-1 improves severe acute kidney injury prediction after pediatric cardiac surgery

ObjectiveAcute kidney injury is a common occurrence after pediatric cardiac surgery and is associated with adverse patient outcomes. Syndecan-1 is a biomarker of endothelial glycocalyx damage, and its early increment after surgery can be associated with acute kidney injury. MethodsWe performed a prospective cohort study with 289 patients aged less than 18 years who underwent cardiac surgery at 1 reference institution. Postoperative plasma syndecan-1 was collected within the first 2 hours after cardiac surgery. Severe acute kidney injury, defined according to Kidney Disease: Improving Global Outcomes stage 2 or 3, doubling of serum creatinine from the preoperative value, or need for dialysis during hospitalization, was the main outcome. Analyses were adjusted for clinical variables and “renal angina index” components (early decrease in estimated creatinine clearance from baseline and increase in percent of intensive care unit fluid overload on the first postoperative day). ResultsPlasma syndecan-1 levels measured early in the postoperative period were independently associated with severe acute kidney injury. The accuracy of postoperative syndecan-1 for the diagnosis of severe acute kidney injury was moderate (area under the curve receiver operating characteristic, 0.77; 95% confidence interval, 0.68-0.85). The addition of syndecan-1 improved the discrimination capacity of a clinical model from 0.80 to 0.86 (P = .004) and improved risk prediction, as measured by net reclassification improvement and integrated discrimination improvement. Postoperative sundecan-1 levels also were independently associated with longer length of intensive care unit and hospital stay. ConclusionsPostoperative plasma syndecan-1 is associated with subsequent severe acute kidney injury and poor outcomes among children undergoing cardiac surgery. It may be useful to identify patients who are at increased risk for acute kidney injury after cardiac surgery.

Traumatic Endotheliopathy: A Prospective Observational Study of 424 Severely Injured Patients.

Objective:Investigate and confirm the association between sympathoadrenal activation, endotheliopathy and poor outcome in trauma patients.Background:The association between sympathoadrenal activation, endotheliopathy, and poor outcome in trauma has only been demonstrated in smaller patient cohorts and animal models but needs confirmation in a large independent patient cohort.Methods:Prospective observational study of 424 trauma patients admitted to a level 1 Trauma Center. Admission plasma levels of catecholamines (adrenaline, noradrenaline) and biomarkers reflecting endothelial damage (syndecan-1, thrombomodulin, and sE-selectin) were measured and demography, injury type and severity, physiology, treatment, and mortality up till 28 days were recorded.Results:Patients had a median ISS of 17 with 72% suffering from blunt injury. Adrenaline and noradrenaline correlated with syndecan-1 (r = 0.38, P < 0.001 and r = 0.23, P < 0.001, respectively) but adrenaline was the only independent predictor of syndecan-1 by multiple linear regression adjusted for age, injury severity score, Glascow Coma Scale, systolic blood pressure, base excess, platelet count, hemoglobin, prehospital plasma, and prehospital fluids (100 pg/mL higher adrenaline predicted 2.75 ng/mL higher syndecan-1, P < 0.001). By Cox analyses adjusted for age, sex, injury severity score, Glascow Coma Scale, base excess, platelet count and hemoglobin, adrenaline, and syndecan-1 were the only independent predictors of both <24-hours, 7-day and 28-day mortality (all P < 0.05). Furthermore, noradrenaline was an independent predictor of <24-hours mortality and thrombomodulin was an independent predictor of 7-day and 28-day mortality (all P < 0.05).Conclusions:We confirmed that sympathoadrenal activation was strongly and independently associated with endothelial glycocalyx and cell damage (ie, endotheliopathy) and furthermore that sympathoadrenal activation and endotheliopathy were independent predictors of mortality in trauma patients.

Evaluation of the endothelial glycocalyx damage in patients with acute coronary syndrome

BackgroundEndothelial glycocalyx (EG) is sugar-based cell-bound surface molecules linked to transmembrane proteins observed on the endothelial surface of the vessels. Damage to this structure causes an increase in platelet and leucocyte adhesion and shear stress in the vessel. We hypothesized a possible link between EG damage and acute coronary syndrome (ACS). MethodsWe measured the syndecan-1 levels (a biomarker of EG damage) in 141 patients (99 men) with ACS and compared to those of 45 patients (24 men) with non-coronary chest pain (NCCP) and of 24 (14 men) healthy individuals (CONTROL). ResultsThe baseline characteristics of the ACS and NCCP groups were similar. Syndecan-1 levels were significantly higher in the ACS group than in the NCCP (p = 0.01) and CONTROL (p = 0.001) groups but did not differ between the NCCP and CONTROL groups (p = 0.83). In analysis according to gender category, the difference among the groups remained significant only for men (p = 0.0009). A syndecan-1 level higher than 148 ng/ml was associated with ACS diagnosis with an odds ratio of 14 (95% confidence interval (CI): 1.8 to 102), p = 0.011. After adjusting for gender, age and current or past tobacco use, this syndecan-1 level remained positively associated with ACS diagnosis with an odds ratio of 12 (95% CI: 1.6 to 93), p = 0.016. ConclusionHigher syndecan-1 levels were observed during ACS, mostly in men, suggesting that EG damage could participate in the atherosclerotic plaque vulnerability process in these patients.

Endothelial glycocalyx damage in patients with acute coronary syndrome

The endothelial glycocalyx is a thin layer of proteinaceous material at the endothelial surface of the vessels. Damage to this structure can cause protein extravasation and tissue edema, increase platelet and leukocyte adhesion and increase of the shear stress in the vessel due to decreasing the nitric oxide production. On the other hand, a vulnerable atherosclerotic plaque with rupture or erosion characterizes the acute coronary syndrome (ACS). The glycocalyx damage could contribute to this process.

HEPARANASE EXPRESSION IN RENAL INTERSTITIAL MAY CONTRIBUTE TO EPITHELIAL AND ENDOTHELIAL CELLS INJURIES AFTER KIDNEY ISCHEMIC/ REPERFUSION EPISODE IN MICE

Kidney ischemia/reperfusion injury (I/R) is the most frequent cause of acute kidney injury (AKI). It had been reported that epithelial and endothelial injuries occurred during kidney I/R injury. Heparanase is an enzyme that degrades glycocalyx and contributes to I/R injury in the heart and liver. This study is to elucidate the association between heparanase expression and cell injuries in kidney I/R injury. We performed kidney I/R injury model in mice using renal pedicle clamping for 30 minutes and sacrificed the mice in day 1 (n=6) after operation. Sham-operation procedure (SO, n=5) was used as control. PAS staining was used to quantify tubular injury score. Serum creatinine was measured from orbital venous. Heparanase expression was quantified using western blot and real-time PCR. Heparanase localization and endothelial injury were shown by immunostaining of heparanase and double glycocalyx-von Willebrand factor. Kidney I/R induced an increase of serum creatinine level that was accompanied by elevation of tubular injury score and glycocalyx damage. Glycocalyx damage was identified using immunofluorescent staining that revealed a disruption of glycocalyx or lectin layer in the endothelial cells of intra-renal artery. This finding was associated with significant elevation of heparanase mRNA and protein level expression. We found that heparanase was expressed in the renal epithelial and interstitial cells. In conclusion, heparanase may induce endothelial and epithelial injury in the kidney I/R episode. Using heparanase expression as a early marker of AKI may possibly promising. Keywords: kidney I/R, epithelial injury, endothelial injury, heparanase, glycocalyx

Endothelial glycocalyx as an orchestrator of vascular homeostasis. New research problems and prospects for vessel wall protection

The functions of endothelial glycocalyx as a regulator of plasma homeostasis and vessel wall homeostasis were considered. The state-of-the-art data of glycocalyx damage by some pathological processes were integrated. The topical task for protection and restoration of the damaged glycocalyx by therapeutic means was formulated. The research approaches for the search for such agents were surveyed and good prospects of multi-disciplinary development of the agents by specialists in different fields were emphasized.

Glycocalyx injury in adults with nephrotic syndrome: Association with endothelial function

BackgroundGlomerulopathy is a group of diseases that affect mainly young adults. Endothelial dysfunction, atherosclerosis, and increased cardiac mortality can complicate the evolution of such patients. However, there is no study evaluating endothelial glycocalyx in this pathology. MethodsThis cross-sectional study included 49 patients with untreated primary nephrotic syndrome that were otherwise healthy. In addition to routine laboratory measurements, syndecan-1, intercellular adhesion molecule-1 (ICAM-1), and e-selectin were measured. Moreover, flow-mediated dilation (FMD) was used as the main endothelial function surrogate. ResultsOf the 49 patients with nephrotic syndrome, 25 (51.0%) were females. The mean age of patients was 39.0±12.1y. FMD was reduced in nephrotic patients in comparison with controls (3.7±1.7 vs. 6.6±1.1%, p<0.001). Nephrotic patients had higher levels of ICAM-1 (616.6±219.7 vs. 356.9±102.0ng/ml, p<0.001) and syndecan-1 (180.3±64.1 vs. 28.2±9.8ng/ml, p<0.001). No significant difference was observed regarding e-selectin (129.9±54.2 vs. 120.2±61.5ng/ml, p=0.489). After adjusting for age and glomerular filtration rate, syndecan-1 was significantly associated with 24-h urinary protein excretion, LDL-cholesterol, HDL-cholesterol, and triglycerides. While age, LDL-cholesterol, and 24-h urinary protein excretion were associated with FMD in the multivariate analysis, when syndecan-1, ICAM-1, and e-selectin were added to the model, only syndecan-1 was independently associated with FMD. ConclusionsWe demonstrated that syndecan-1, a marker of endothelial glycocalyx damage, is increased in patients with nephrotic syndrome and near-normal renal function. Moreover, we determined its association with nephrotic syndrome features and suggest it can have a role in the endothelial dysfunction of these patients.

Plasma free hemoglobin and microcirculatory response to fresh or old blood transfusions in sepsis.

BackgroundFree hemoglobin (fHb) may induce vasoconstriction by scavenging nitric oxide. It may increase in older blood units due to storage lesions. This study evaluated whether old red blood cell transfusion increases plasma fHb in sepsis and how the microvascular response may be affected.MethodsThis is a secondary analysis of a randomized study. Twenty adult septic patients received either fresh or old (<10 or >15 days storage, respectively) RBC transfusions. fHb was measured in RBC units and in the plasma before and 1 hour after transfusion. Simultaneously, the sublingual microcirculation was assessed with sidestream-dark field imaging. The perfused boundary region was calculated as an index of glycocalyx damage. Tissue oxygen saturation (StO2) and Hb index (THI) were measured with near-infrared spectroscopy and a vascular occlusion test was performed.ResultsSimilar fHb levels were found in the supernatant of fresh and old RBC units. Despite this, plasma fHb increased in the old RBC group after transfusion (from 0.125 [0.098–0.219] mg/mL to 0.238 [0.163–0.369] mg/mL, p = 0.006). The sublingual microcirculation was unaltered in both groups, while THI increased. The change in plasma fHb was inversely correlated with the changes in total vessel density (r = -0.57 [95% confidence interval -0.82, -0.16], p = 0.008), De Backer score (r = -0.63 [95% confidence interval -0.84, -0.25], p = 0.003) and THI (r = -0.72 [95% confidence interval -0.88, -0.39], p = 0.0003).ConclusionsOld RBC transfusion was associated with an increase in plasma fHb in septic patients. Increasing plasma fHb levels were associated with decreased microvascular density.Trial RegistrationClinicalTrials.gov NCT01584999

Endothelial glycocalyx damage is associated with leptospirosis acute kidney injury.

Leptospirosis is a common disease in tropical countries, and the kidney is one of the main target organs. Membrane proteins of Leptospira are capable of causing endothelial damage in vitro, but there have been no studies in humans evaluating endothelial glycocalyx damage and its correlation with acute kidney injury (AKI). We performed a cohort study in an outbreak of leptospirosis among military personnel. AKI was diagnosed in 14 of 46 (30.4%) patients. Leptospirosis was associated with higher levels of intercellular adhesion molecule-1 (ICAM-1; 483.1 ± 31.7 versus 234.9 ± 24.4 mg/L, P < 0.001) and syndecan-1 (73.7 ± 15.9 versus 21.2 ± 7.9 ng/mL, P < 0.001) compared with exposed controls. Patients with leptospirosis-associated AKI had increased level of syndecan-1 (112.1 ± 45.4 versus 41.5 ± 11.7 ng/mL, P = 0.021) and ICAM-1 (576.9 ± 70.4 versus 434.9 ± 35.3, P = 0.034) compared with leptospirosis patients with no AKI. Association was verified between syndecan-1 and ICAM-1 with serum creatinine elevation and neutrophil gelatinase-associated lipocalin (NGAL) levels. This association remained even after multivariate analysis including other AKI-associated characteristics. Endothelial injury biomarkers are associated with leptospirosis-associated renal damage.

Syndecan-1 in Acute Decompensated Heart Failure--Association With Renal Function and Mortality.

Heart failure (HF) is a leading cause of hospitalization throughout the world, and the mortality rate remains elevated. HF is frequently complicated by acute kidney injury (AKI), worsening the patient's prognosis. There have been no studies evaluating the role that endothelial glycocalyx damage plays in HF patients and its association with AKI and mortality. We measured several endothelial biomarkers in 201 consecutive patients with acute decompensated HF (ADHF) during emergency department (ED) admission. In-hospital mortality, AKI development and 6-month mortality rates were assessed. ADHF patients with worsening renal function had higher levels of syndecan-1 but not those patients with stable chronic kidney disease. Syndecan-1 levels during ED admission were predictive for AKI during the hospital stay (AUC 0.741, P<0.001) and had an even better discriminatory capacity in more severe AKI (AUC 0.812, P<0.001). Additionally, after adjusting for several confounding factors, including biomarkers of endothelial function and endothelial cell activation, syndecan-1 remained associated with in-hospital mortality rates. On a Cox multivariate analysis regression, syndecan-1 was associated with 6-month mortality rates. The concentration of syndecan-1, a marker of glycocalyx damage measured during ED admission, is valuable in assessing the risk of developing AKI and in-hospital mortality. Its association with mortality is strong after 6-month follow-up.

Sympathoadrenal activation and endothelial damage in patients with varying degrees of acute infectious disease: An observational study

PurposeTo investigate levels, associations between, and predictive value of plasma catecholamines and biomarkers of endothelial damage in patients with acute infectious illness stratified according to infection type and sepsis severity. Material and MethodsThis is a post hoc study of plasma samples collected in prospective studies conducted at a department of internal medicine. Plasma catecholamines, syndecan-1, and thrombomodulin were measured. Registration of biochemistry, physiology, and 28- and 90-day mortality was performed. ResultsPatients (n = 321) were stratified into 5 groups: no infection (n = 50), local infection (n = 63), sepsis (n = 95), severe sepsis (n = 100), or septic shock (n = 13). Median Sequential Organ Failure Assessment (SOFA) score in all patients was 2, and 28- and 90-day mortality was 6% and 10%. Syndecan-1 and thrombomodulin increased progressively across groups with increasing disease severity (both P < .001), correlating with SOFA score in all groups (ρ = 0.24-0.87, all P < .05). Plasma noradrenaline, syndecan-1, and thrombomodulin were higher in nonsurvivors (P < .05) and by log-rank test, levels above median predicted increased 28-day (noradrenaline and syndecan-1, P < .05) and 90-day (thrombomodulin, P < .05) mortality. ConclusionsBiomarkers of endothelial glycocalyx and cell damage increased with increasing acute infectious disease severity, correlated with SOFA score, and predicted mortality together with plasma noradrenaline. Sympathoadrenal activation and endothelial damage are linked to disease pathology also in less sick patients.

Clinical use of hydroxyethyl starch and serious adverse effects: Need for awareness amongst the medical fraternity

Clinical use of hydroxyethyl starch and serious adverse effects: Need for awareness amongst the medical fraternity

Acute enzymatic glycocalyx degradation results in reduced insulin sensitivity but normal glucose tolerance in conscious rats

Perturbation of the endothelial glycocalyx has been suggested to be an early event in the development of endothelial dysfunction during increased cardiovascular risk exposure. Previously, we showed in anesthetized rats that acute enzymatic degradation of the endothelial glycocalyx was associated with impaired insulin-mediated glucose disposal, suggesting a role of the glycocalyx in regulation of glucose homeostasis. In the current study, we tested the acute effect of enzymatic glycocalyx treatment on glucose tolerance and insulin sensitivity in conscious rats. In rats that had had their femoral artery and vein cannulated 1 week before the experiment, intravenous glucose and insulin tolerance tests were performed before and after acute degradation of the endothelial glycocalyx using an intravenous bolus of hyaluronidase. During the intravenous glucose tolerance test, glucose tolerance did not differ between the hyaluronidase-treated and control animals, but was associated with a 1.5-fold higher plasma insulin level in the former group. Further, glycocalyx treatment significantly decreased insulin-mediated glucose disposal during intravenous insulin tolerance tests, as observed from the reduced insulin-mediated glucose disposal rate from 3.3±0.1%/min in control rats to 2.6±0.2%/min in the hyaluronidase-treated rats. These results support a role for the endothelial glycocalyx in the regulation of peripheral insulin sensitivity. The reduction in insulin sensitivity during acute glycocalyx damage, however, does not have an immediate effect on glucose tolerance because of a compensatory increase in plasma insulin levels.

The endothelial glycocalyx: a review of the vascular barrier.

The endothelial glycocalyx is an important part of the vascular barrier. The glycocalyx is intimately linked to the homoeostatic functions of the endothelium. Damage to the glycocalyx precedes vascular pathology. In the first part of this paper, we have reviewed the structure, physiology and pathology of the endothelial glycocalyx, based on a literature search of the past five years. In the second part, we have systematically reviewed interventions to protect or repair the glycocalyx. Glycocalyx damage can be caused by hypervolaemia and hyperglycaemia and can be prevented by maintaining a physiological concentration of plasma protein, particularly albumin. Other interventions have been investigated in animal models: these require clinical research before their introduction into medical practice.

Damage of the endothelial glycocalyx in chronic kidney disease

Background and objectivesThe endothelial glycocalyx (eGC), a mesh of anionic biopolymers covering the luminal surface of endothelial cells, is considered as an intravascular compartment that protects the vessel wall against pathogenic insults in cardiovascular disease. We hypothesized that chronic kidney disease (CKD) is associated with reduced eGC integrity and subsequent endothelial dysfunction. Methods & resultsShedding of two major components of the eGC, namely syndecan-1 (Syn-1) and hyaluronan (HA), was measured by ELISA in 95 patients with CKD (stages 3–5) and 31 apparently healthy controls. Plasma levels of Syn-1 and HA increased steadily across CKD stages (5- and 5.5-fold, respectively P < 0.001) and were independently associated with impaired renal function after multivariate adjustment. Furthermore, Syn-1 and HA correlated tightly with plasma markers of endothelial dysfunction such as soluble fms-like tyrosine kinase-1 (sFlt-1), soluble vascular adhesion molecule-1 (sVCAM-1), von-Willebrand-Factor (vWF) and angiopoietin-2 (P < 0.001). Experimentally, excessive shedding of the eGC, evidenced by 11-fold increased Syn-1 plasma levels, was also observed in an established rat model of CKD, the 5/6-nephrectomized rats. Consistently, an atomic force microscopy-based approach evidenced a significant decrease in eGC thickness (360 ± 79 vs. 157 ± 29 nm, P = 0.001) and stiffness (0.33 ± 0.02 vs. 0.22 ± 0.01 pN/nm, P < 0.001) of aorta endothelial cell explants isolated from CKD rats. ConclusionOur findings provide evidence for damage of the atheroprotective eGC as a consequence of CKD and potentially open a new avenue to pathophysiology and treatment of cardiovascular disease in renal patients.

Early impairment of skeletal muscle endothelial glycocalyx barrier properties in diet-induced obesity in mice.

While previous studies have indicated an important role for the endothelial glycocalyx in regulation of microvascular function, it was recently shown that acute enzymatic glycocalyx degradation in rats was associated with an impaired insulin‐mediated glucose disposal. The aim of this study was to determine whether glycocalyx damage in skeletal muscle occurs at an early stage of diet‐induced obesity (DIO). The microcirculation of the hindlimb muscle of anesthetized C57Bl/6 mice, fed chow (CON) or a high‐fat diet (HFD) for 6 and 18 weeks (w), respectively, was visualized with a Sidestream Dark‐Field camera, and glycocalyx barrier properties were derived from the calculated perfused boundary region (PBR). Subsequently, an intraperitoneal glucose tolerance test was performed and the area under the curve (AUC) of blood glucose was calculated. Impairment of glycocalyx barrier properties was already apparent after 6 weeks of HFD and remained after 18 weeks of HFD (PBR [in μm]: 0.81 ± 0.03 in CON_6w vs. 0.97 ± 0.04 in HFD_6w and 1.02 ± 0.07 in HFD_18w [both P < 0.05]). Glucose intolerance appeared to develop more slowly (AUC [in mmol/L × 120 min]: 989 ± 61 in CON_6w vs. 1204 ± 89 in HFD_6w [P = 0.11] and 1468 ± 84 in HFD_18w [P < 0.05]) than the impairment of glycocalyx barrier properties. The data indicate that damage to the endothelial glycocalyx is an early event in DIO. It is suggested that glycocalyx damage may contribute to the development of insulin resistance in obesity.

Microcirculatory effects of the transfusion of leukodepleted or non-leukodepleted red blood cells in patients with sepsis: a pilot study

IntroductionMicrovascular alterations impair tissue oxygenation during sepsis. A red blood cell (RBC) transfusion increases oxygen (O2) delivery but rarely improves tissue O2 uptake in patients with sepsis. Possible causes include RBC alterations due to prolonged storage or residual leukocyte-derived inflammatory mediators. The aim of this study was to compare the effects of two types of transfused RBCs on microcirculation in patients with sepsis.MethodsIn a prospective randomized trial, 20 patients with sepsis were divided into two separate groups and received either non-leukodepleted (n = 10) or leukodepleted (n = 10) RBC transfusions. Microvascular density and perfusion were assessed with sidestream dark field (SDF) imaging sublingually, before and 1 hour after transfusions. Thenar tissue O2 saturation (StO2) and tissue hemoglobin index (THI) were determined with near-infrared spectroscopy, and a vascular occlusion test was performed. The microcirculatory perfused boundary region was assessed in SDF images as an index of glycocalyx damage, and glycocalyx compounds (syndecan-1, hyaluronan, and heparan sulfate) were measured in the serum.ResultsNo differences were observed in microvascular parameters at baseline and after transfusion between the groups, except for the proportion of perfused vessels (PPV) and blood flow velocity, which were higher after transfusion in the leukodepleted group. Microvascular flow index in small vessels (MFI) and blood flow velocity exhibited different responses to transfusion between the two groups (P = 0.03 and P = 0.04, respectively), with a positive effect of leukodepleted RBCs. When within-group changes were examined, microcirculatory improvement was observed only in patients who received leukodepleted RBC transfusion as suggested by the increase in De Backer score (P = 0.02), perfused vessel density (P = 0.04), PPV (P = 0.01), and MFI (P = 0.04). Blood flow velocity decreased in the non-leukodepleted group (P = 0.03). THI and StO2 upslope increased in both groups. StO2 and StO2 downslope increased in patients who received non-leukodepleted RBC transfusions. Syndecan-1 increased after the transfusion of non-leukodepleted RBCs (P = 0.03).ConclusionsThis study does not show a clear superiority of leukodepleted over non-leukodepleted RBC transfusions on microvascular perfusion in patients with sepsis, although it suggests a more favorable effect of leukodepleted RBCs on microcirculatory convective flow. Further studies are needed to confirm these findings.Trial registrationClinicalTrials.gov, NCT01584999

Nanomechanics of the Endothelial Glycocalyx in Experimental Sepsis

The endothelial glycocalyx (eGC), a carbohydrate-rich layer lining the luminal side of the endothelium, regulates vascular adhesiveness and permeability. Although central to the pathophysiology of vascular barrier dysfunction in sepsis, glycocalyx damage has been generally understudied, in part because of the aberrancy of in vitro preparations and its degradation during tissue handling. The aim of this study was to analyze inflammation-induced damage of the eGC on living endothelial cells by atomic-force microscopy (AFM) nanoindentation technique. AFM revealed the existence of a mature eGC on the luminal endothelial surface of freshly isolated rodent aorta preparations ex vivo, as well as on cultured human pulmonary microvascular endothelial cells (HPMEC) in vitro. AFM detected a marked reduction in glycocalyx thickness (266 ± 12 vs. 137 ± 17 nm, P<0.0001) and stiffness (0.34 ± 0.03 vs. 0.21 ± 0.01 pN/mn, P<0.0001) in septic mice (1 mg E. coli lipopolysaccharides (LPS)/kg BW i.p.) compared to controls. Corresponding in vitro experiments revealed that sepsis-associated mediators, such as thrombin, LPS or Tumor Necrosis Factor-α alone were sufficient to rapidly decrease eGC thickness (-50%, all P<0.0001) and stiffness (-20% P<0.0001) on HPMEC. In summary, AFM nanoindentation is a promising novel approach to uncover mechanisms involved in deterioration and refurbishment of the eGC in sepsis.

The aPC treatment improves microcirculation in severe sepsis/septic shock syndrome

BackgroundThe role of recombinant activated protein C (aPC) during sepsis is still controversial. It showed anti-inflammatory effect and improved the microvascular perfusion in experimental models of septic shock. The present study was aimed at testing the hypothesis that recombinant aPC therapy improves the microcirculation during severe sepsis.MethodsProspective observational study on patients admitted in a 12-beds intensive care unit of a university hospital from July 2010 to December 2011, with severe sepsis and at least two sepsis-induced organ failures occurring within 48 hours from the onset of sepsis, who received an infusion of aPC (24 mcg/kg/h for 96 hours) (aPC group). Patients with contraindications to aPC administration were also monitored (no-aPC group).At baseline (before starting aPC infusion, T0), after 24 hours (T1a), 48 hours (T1b), 72 hours (T1c) and 6 hours after the end of aPC infusion (T2), general clinical and hemodynamic parameters were collected and the sublingual microcirculation was evaluated with sidestream dark-field imaging. Total vessel density (TVD), perfused vessel density (PVD), De Backer score, microvascular flow index (MFIs), the proportion of perfused vessels (PPV) and the flow heterogeneity index (HI) were calculated for small vessels. The perfused boundary region (PBR) was measured as an index of glycocalyx damage. Variables were compared between time points and groups using non parametric or parametric statistical tests, as appropriate.ResultsIn the 13 aPC patients mean arterial pressure (MAP), base excess, lactate, PaO2/FiO2 and the Sequential Organ Failure Assessment (SOFA) score significantly improved over time, while CI and ITBVI did not change. MFIs, TVD, PVD, PPV significantly increased over time and the HI decreased (p < 0.05 in all cases), while the PBR did not change. No-aPC patients (n = 9) did not show any change in the microcirculation over time. A positive correlation was found between MFIs and MAP. TVD, PVD and De Backer score negatively correlated with norepinephrine dose, and the SOFA score negatively correlated with MFIs, TVD and PVD.ConclusionsaPC significantly improves the microcirculation in patients with severe sepsis/septic shock.Trial registrationNCT01806428